SONARJAVA-6253 Ensure integration tests do not share cache

[tomasz-tylenda-sonarsource]

Use separate caches for plugin, ruling, and other ITs. See SONARJAVA-6253 for details.

[hashicorp-vault-sonar-prod]

SONARJAVA-6253

[sonar-review-alpha]

Summary

This PR fixes cache sharing between integration test jobs in the CI pipeline. Different test jobs (ruling, plugin, sanity, autoscan, etc.) were previously sharing the same Maven dependency cache, which could cause test flakiness or failure propagation. The fix introduces separate cache keys for each job by writing a job-specific file before Maven runs—since GitHub's Maven caching is based on pom.xml hashing, this forces each job to have an isolated cache.

What reviewers should know

How it works:

• New custom action .github/actions/write-file writes a sentinel file to target/just_for_cache_key_calculation/pom.xml before Maven runs
• Each job includes its name (and matrix variables for parameterized jobs) in the file content, making the cache key unique per job variant
• This prevents cache collisions between ruling-qa, plugin-qa, sanity, custom-rules-license-check, autoscan, and qa-os-win jobs

Where to look:

• .github/actions/write-file/action.yml - the new helper action (straightforward bash file write)
• build.yml jobs - each test job now has an "Ensure Separate Job Cache Key" step before Maven configuration
• Matrix jobs like ruling-qa and plugin-qa include their matrix variables in the cache key; single-run jobs only use the job name

Design notes:

• The file path and name are intentional: target/ keeps it out of source control, just_for_cache_key_calculation/ signals its purpose clearly
• Step placement is important: it runs after checkout but before Maven is configured, ensuring the file exists when the cache is initialized
• No test coverage changes needed—this is pure infrastructure/CI work

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🗣️ Give feedback

[tomasz-tylenda-sonarsource]

I have an alternative fix in #5567 and SonarSource/ci-github-actions#244

[tomasz-tylenda-sonarsource]

I think we should proceed with this workaround, while consider a more general fix for more repos.

[sonarqube-next]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
0 Dependency risks
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarQube

[sonar-review-alpha]

LGTM! ✅

🗣️ Give feedback

[alban-auzeill]

LGTM