Enable ci_pipeline_status_omit_commit_sha_in_cache_key FF by default

What does this MR do?

Enable ci_pipeline_status_omit_commit_sha_in_cache_key FF by default. This has been enabled globally for 3 days since #229139 (comment 386306207)

Resolves #229139 (closed)

Due to #232337, I am leaving the flag in so that instances can disable this.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry, changelog already present in !33712 (diffs)
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.