Improve `TestEnv` for cleaner tests #12750

Job	Run time
analyze-other (actions)	45s
analyze-other (python)	50s
check-codeql-versions	16s
analyze-javascript (ubuntu-22.04, linked)	3m 36s
analyze-javascript (macos-14-xlarge)	2m 28s
analyze-javascript (macos-15-xlarge, linked)	2m 28s
analyze-javascript (macos-15-xlarge)	2m 29s
analyze-javascript (ubuntu-22.04)	4m 18s
analyze-javascript (ubuntu-24.04, linked)	4m 15s
analyze-javascript (macos-14-xlarge, linked)	2m 43s
analyze-javascript (windows-2022, linked)	6m 12s
analyze-javascript (windows-2025)	6m 28s
analyze-javascript (windows-2025, linked)	6m 9s
analyze-javascript (windows-2022)	6m 27s
analyze-javascript (ubuntu-24.04)	4m 36s
	54m 0s

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