Guard eclipse() to spotless tasks and keep P2 mirror on pinned version (security)

[peterzhuamazon]

Description

Guard eclipse() to spotless tasks and keep P2 mirror on pinned version. The guard and mirror already landed in #6438; this PR adds the version pin.

Issues Resolved

opensearch-project/opensearch-build#6421

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[github-actions]

PR Code Analyzer ❗

AI-powered 'Code-Diff-Analyzer' found issues on commit ddd9fec.

⛔ Hard block: Issues at High severity or above will block this PR from merging.

Path	Line	Severity	Description
build.gradle	61	high	Build plugin version change: 'com.diffplug.spotless' upgraded from 6.25.0 to 8.10.1 — a major version bump (v6→v8). Per mandatory supply chain policy, all build plugin version changes must be flagged for maintainer verification. Artifact authenticity cannot be confirmed without checking the Gradle plugin portal.
gradle/formatting.gradle	25	high	Eclipse formatter artifact version explicitly pinned to '4.29', changing what artifact is resolved at build time. This is a build-time dependency change (fetched via P2 mirror) and must be verified by maintainers to confirm the artifact resolves to the expected Eclipse release and has not been tampered with.

The table above displays the top 10 most important findings.

Total: 2 | Critical: 0 | High: 2 | Medium: 0 | Low: 0

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Pull Requests Author(s): Please update your Pull Request according to the report above.

Repository Maintainer(s): You can bypass diff analyzer by adding label skip-diff-analyzer after reviewing the changes carefully, then re-run failed actions. To re-enable the analyzer, remove the label, then re-run all actions.

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⚠️ Note: The Code-Diff-Analyzer helps protect against potentially harmful code patterns. Please ensure you have thoroughly reviewed the changes beforehand.

Thanks.

[peterzhuamazon]

expected version pin

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.75%. Comparing base (c33b831) to head (ddd9fec).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6461      +/-   ##
==========================================
- Coverage   75.75%   75.75%   -0.01%     
==========================================
  Files         457      457              
  Lines       30508    30508              
  Branches     4615     4615              
==========================================
- Hits        23111    23110       -1     
- Misses       5276     5278       +2     
+ Partials     2121     2120       -1     

see 7 files with indirect coverage changes

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