chore: Deprecate the enable_metrics option

[szokeasaurusrex]

Providing the ability to disable sending metrics is somewhat of a footgun, as this flag can prevent all Sentry metrics from being sent, so this change turns that option into a no-op, ensuring metrics are always enabled.

Metrics are only sent when users explicitly record them with the metrics APIs we provide. Users who do not want metrics can stop using those APIs.

Resolves #1298
Resolves RUST-275

[linear-code]

RUST-275

[sentry-warden]

Client::with_options docs omit new enable_metrics panic

The # Panics docs for with_options were not updated to mention the new enable_metrics debug_assert!, so users are only warned about the enable_logs panic condition.

Evidence

• The with_options rustdoc (lines 173-174) says: "Panics in debug builds if the deprecated no-op field enable_logs is set to false."
• The hunk adds debug_assert!(options.enable_metrics) inside with_options at lines 184-188.
• The #[expect(deprecated)] block comment was updated from singular "field" to plural "fields" to cover both assertions, confirming the docs were not kept in sync.

Also found at 1 additional location

• sentry-core/src/clientoptions.rs:256

_{Identified by Warden · docs-review · D8M-MS5}

[sentry-warden]

enable_metrics builder docs copy-paste typo

The updated docs for the ClientOptions::enable_metrics builder method incorrectly say "We only capture logs" instead of "metrics". Fix the sentence to refer to metrics APIs.

Evidence

• sentry-core/src/clientoptions.rs:705-706 in the enable_metrics builder docs read: "We only capture logs if you explicitly call the relevant APIs."
• The preceding enable_logs builder at clientoptions.rs:690 correctly says "We only capture logs if you explicitly call the relevant APIs or if you enable an integration that captures logs."
• The enable_metrics builder docs immediately above the typo correctly say "To stop sending metrics, simply remove any calls to our metrics APIs."
• The enable_metrics method is public and deprecated in this change set, so its rustdoc is user-facing.

Also found at 3 additional locations

• sentry-core/src/client/mod.rs:120
• sentry-core/src/clientoptions.rs:707
• sentry-core/src/clientoptions.rs:845-848

_{Identified by Warden · docs-review · CN8-BFY}

[sentry-warden]

Fix attempt detected (commit 469f7a8)

The commit directly updates the enable_metrics documentation but leaves the sentence incorrectly saying that only logs are captured instead of metrics.

The original issue appears unresolved. Please review and try again.

_{Evaluated by Warden}