Remove `disable_combine_sarif_files` feature flag #5186

Job	Run time
Ruby analysis (ubuntu-latest, linked)	1m 3s
Ruby analysis (macos-latest, linked)	1m 17s
Ruby analysis (ubuntu-latest, nightly-latest)	1m 7s
Ruby analysis (ubuntu-latest, default)	1m 9s
Ruby analysis (macos-latest, default)	1m 30s
Ruby analysis (macos-latest, nightly-latest)	1m 59s
	8m 5s

Provide feedback