Migrate from Commons Lang 2 to Commons Lang 3

[timja-bot]

Migrate from deprecated/EOL Commons Lang 2 to Commons Lang 3.

Part of the effort to remove Commons Lang 2 from Jenkins core — jenkinsci/jenkins#16404,
jenkinsci/jenkins#26105. Commons Lang 2 is EOL and carries an unfixed advisory
(GHSA-j288-q9x7-2f5v).

What's changed

• Renamed every org.apache.commons.lang.* import to org.apache.commons.lang3.* (8 files) and
  declared io.jenkins.plugins:commons-lang3-api explicitly rather than relying on a transitive
  copy.
• ExceptionUtils.getFullStackTrace(e) is getStackTrace(e) in Lang 3.
• Bumped the parent POM to 6.2211.v27f680c93c53 so the ban-commons-lang-2 enforcer rule is
  available, and enabled it.

trimToNull / trimToEmpty / isEmpty / isBlank behave identically in Lang 3, so this is a
package rename with no semantic change.

Testing done

mvn -B -ntp clean verify passes locally on Java 21 / macOS.
The ban-commons-lang-2 enforcer rule is enabled in this PR, so the build fails if an
org.apache.commons.lang.* import comes back.

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests that demonstrate the feature works or the issue is fixed

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🤖 This pull request was generated with AI assistance (Claude Code) as part of a bulk migration
across Jenkins plugins. If anything here looks wrong, please comment on this PR or contact @timja.