fix(joiner): resolve race condition

[gacevicljubisa]

Checklist

• [x] I have read the coding guide.
• [ ] My change requires a documentation update, and I have done it.
• [ ] I have added tests to cover my changes.
• [x] I have filled out the description and linked the related issues.

Description

Fixes a race condition in pkg/file/joiner that caused CI test timeouts. Refactored decoderCache.GetOrCreate to prevent deadlocks by correctly managing mutex locks around getter.New calls.

Makefile: Filter linker warnings and disable test caching for test-ci-race

Open API Spec Version Changes (if applicable)

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