[bridge] refactor test utils #66286

Job	Run time
diff	8s
license-check	1m 17s
test-extra (ubuntu-ghcloud)	12m 12s
windows-build (windows-ghcloud)	17m 37s
release-notes-check	5s
test (ubuntu-ghcloud)	20m 40s
simtest	13m 52s
move-test	0s
test	0s
cargo-deny (advisories, licenses, bans, ...)	2m 53s
clippy	3m 58s
rustfmt	24s
test-extra	0s
cutting a new execution layer	1m 40s
graphql-rpc	26m 13s
bridge-evm-tests	0s
	1h 40m 59s

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