feat(observability): backend metrics + tracing primitives

[Ma77Ball]

What changes were proposed in this PR?

Adds the libraries services use to emit metrics and distributed traces. These stay dormant until the SDK is enabled in PR1.

• TexeraMetrics: metric instruments for workflow lifecycle and throughput. The active-executions metric is modeled as an observable gauge read from the live registry, correcting the phantom-active count a manual up/down counter produced.
• TexeraTracer and SpanAttrs: helpers for creating spans and attaching standardized attributes.
• TraceparentValidator: parses and validates W3C traceparent headers for context propagation.
• Pure additions to the Config module; no behavior changes when telemetry is disabled.

Any related issues, documentation, or discussions?

Closes: #5368
Part of #4070. Stacked on #5375.

How was this PR tested?

• Unit specs for the metrics, tracer, span-attribute, and traceparent-validator classes.
• sbt scalafmtCheckAll passes; compile and tests run in this PR's CI.

Was this PR authored or co-authored using generative AI tooling?

Co-authored with Claude Opus 4.8 in compliance with ASF

[codecov-commenter]

Codecov Report

❌ Patch coverage is 68.51852% with 119 lines in your changes missing coverage. Please review.
✅ Project coverage is 55.22%. Comparing base (0a5693c) to head (b311b57).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
...ala/org/apache/texera/observability/OtelInit.scala	63.30%	43 Missing and 8 partials ⚠️
...org/apache/texera/observability/TexeraTracer.scala	0.00%	14 Missing ⚠️
...rg/apache/texera/observability/TexeraMetrics.scala	84.93%	4 Missing and 7 partials ⚠️
...ra/web/observability/WorkflowMetricsRecorder.scala	44.44%	8 Missing and 2 partials ⚠️
...la/org/apache/texera/observability/SpanAttrs.scala	66.66%	8 Missing and 2 partials ⚠️
...e/texera/observability/TexeraOtelLogAppender.scala	72.22%	4 Missing and 6 partials ⚠️
...rg/apache/texera/web/service/WorkflowService.scala	0.00%	6 Missing ⚠️
...la/org/apache/texera/web/ComputingUnitMaster.scala	0.00%	2 Missing ⚠️
...org/apache/texera/observability/LogSanitizer.scala	96.42%	0 Missing and 1 partial ⚠️
.../texera/service/ComputingUnitManagingService.scala	0.00%	1 Missing ⚠️
... and 3 more

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #5376      +/-   ##
============================================
- Coverage     55.27%   55.22%   -0.06%     
- Complexity     2991     2999       +8     
============================================
  Files          1117     1123       +6     
  Lines         43258    43401     +143     
  Branches       4668     4701      +33     
============================================
+ Hits          23912    23969      +57     
- Misses        17938    18019      +81     
- Partials       1408     1413       +5     

Flag	Coverage Δ		*Carryforward flag
access-control-service	70.14% <100.00%> (+0.14%)	⬆️
agent-service	34.36% <ø> (ø)		Carriedforward from 43ca4b2
amber	58.01% <69.16%> (+0.21%)	⬆️
computing-unit-managing-service	0.00% <0.00%> (ø)
config-service	50.76% <0.00%> (-0.80%)	⬇️
file-service	58.88% <0.00%> (-0.15%)	⬇️
frontend	48.42% <ø> (-0.46%)	⬇️	Carriedforward from 43ca4b2
notebook-migration-service	78.57% <ø> (ø)
pyamber	90.20% <ø> (ø)		Carriedforward from 43ca4b2
python	90.76% <ø> (ø)		Carriedforward from 43ca4b2
workflow-compiling-service	54.74% <0.00%> (-0.41%)	⬇️

*This pull request uses carry forward flags. Click here to find out more.

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[github-actions]

⚠️ Benchmark changes need a look

🟢 0 better · 🔴 7 worse · ⚪ 8 noise (<±5%) · 0 without baseline

Compared against main 0a5693c benchmarked on this same runner, so the delta is largely free of cross-runner hardware noise. The "7d avg" column still reflects the gh-pages dashboard. Treat <±5% as noise unless repeated.

Dashboard · Run

	config	throughput	MB/s	latency	max Δ latest / 7d
🔴	bs=10 sw=10 sl=64	383	0.234	26,339/32,648/32,648 us	🔴 +18.5% / 🔴 +111.1%
🔴	bs=100 sw=10 sl=64	806	0.492	123,598/140,837/140,837 us	🔴 +13.3% / 🔴 +28.0%
⚪	bs=1000 sw=10 sl=64	929	0.567	1,079,342/1,117,970/1,117,970 us	⚪ within ±5% / 🔴 +6.3%

Baseline details

Latest main 0a5693c from same runner

config	metric	PR	latest main	7d avg	Δ latest	Δ 7d
bs=10 sw=10 sl=64	throughput	383 tuples/sec	436 tuples/sec	756.6 tuples/sec	-12.2%	-49.4%
bs=10 sw=10 sl=64	MB/s	0.234 MB/s	0.266 MB/s	0.462 MB/s	-12.0%	-49.3%
bs=10 sw=10 sl=64	p50	26,339 us	22,227 us	13,009 us	+18.5%	+102.5%
bs=10 sw=10 sl=64	p95	32,648 us	32,197 us	15,463 us	+1.4%	+111.1%
bs=10 sw=10 sl=64	p99	32,648 us	32,197 us	18,561 us	+1.4%	+75.9%
bs=100 sw=10 sl=64	throughput	806 tuples/sec	860 tuples/sec	963.83 tuples/sec	-6.3%	-16.4%
bs=100 sw=10 sl=64	MB/s	0.492 MB/s	0.525 MB/s	0.588 MB/s	-6.3%	-16.4%
bs=100 sw=10 sl=64	p50	123,598 us	117,964 us	103,320 us	+4.8%	+19.6%
bs=100 sw=10 sl=64	p95	140,837 us	124,352 us	110,058 us	+13.3%	+28.0%
bs=100 sw=10 sl=64	p99	140,837 us	124,352 us	118,543 us	+13.3%	+18.8%
bs=1000 sw=10 sl=64	throughput	929 tuples/sec	926 tuples/sec	989.07 tuples/sec	+0.3%	-6.1%
bs=1000 sw=10 sl=64	MB/s	0.567 MB/s	0.565 MB/s	0.604 MB/s	+0.4%	-6.1%
bs=1000 sw=10 sl=64	p50	1,079,342 us	1,078,611 us	1,015,599 us	+0.1%	+6.3%
bs=1000 sw=10 sl=64	p95	1,117,970 us	1,130,759 us	1,055,944 us	-1.1%	+5.9%
bs=1000 sw=10 sl=64	p99	1,117,970 us	1,130,759 us	1,086,834 us	-1.1%	+2.9%

Raw CSV

config_idx,batch_size,schema_width,string_len,num_batches,total_ms,total_tuples,total_bytes,tuples_per_sec,mb_per_sec,lat_p50_us,lat_p95_us,lat_p99_us
0,10,10,64,20,522.27,200,128000,383,0.234,26338.79,32648.39,32648.39
1,100,10,64,20,2481.83,2000,1280000,806,0.492,123598.07,140837.38,140837.38
2,1000,10,64,20,21520.79,20000,12800000,929,0.567,1079341.88,1117969.71,1117969.71

[github-actions]

Automated Reviewer Suggestions

Based on the git blame history of the changed files, we recommend the following reviewers:

• Contributors with relevant context: @bobbai00, @Yicong-Huang, @aglinxinyuan
  You can notify them by mentioning @bobbai00, @Yicong-Huang, @aglinxinyuan in a comment.