Add policy to exclude env vars. #13610

Job	Run time
towncrier_check	8s
check_if_release_branch	1s
changed_files	6s
build mirrord CLI	0s
test_agent	3m 15s
lint	4m 50s
check-rust-docs	2m 8s
macos_tests	21m 12s
integration_tests	13m 38s
test_agent_image	6m 16s
test_cli_image	5m 55s
lint_markdown	0s
e2e (docker)	14m 6s
intellij_e2e_on_release_branch	0s
vscode_e2e_on_release_branch	0s
e2e (containerd)	14m 6s
ci	1s
	1h 25m 42s

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