Make `config.nix` shims #1708

Job	Run time
Check Cachix and Docker secrets present for installer tests	1s
vm_tests	17m 54s
tests (ubuntu-latest)	30m 10s
tests (macos-latest)	38m 1s
flake_regressions	15m 0s
installer	0s
docker_push_image	0s
installer_test	0s
	1h 41m 6s

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