Improve cross-domain mirrors test #4542

Job	Run time
check format (ubuntu-latest / nightly)	11s
test (ubuntu-latest / stable)	10m 54s
test (macos-latest / stable)	9m 51s
check docs (ubuntu-latest / stable)	1m 14s
check examples (ubuntu-latest / stable)	58s
test (windows-latest / stable)	13m 35s
check feature flags (ubuntu-latest / stable)	16m 41s
check licenses (ubuntu-latest / stable)	22s
check linter (ubuntu-latest / stable)	1m 54s
check minimal supported rust version (ubuntu-latest / msrv)	52s
check minimal versions of transitive dependencies (ubuntu-latest / stable)	1m 36s
check spelling (ubuntu-latest / nightly)	6m 14s
	1h 4m 22s

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