[bridge] refactor test utils #66301

Job	Run time
diff	10s
license-check	1m 11s
release-notes-check	4s
test (ubuntu-ghcloud)	19m 54s
test-extra (ubuntu-ghcloud)	12m 43s
windows-build (windows-ghcloud)	13m 56s
simtest	14m 1s
move-test	0s
test-extra	0s
test	0s
clippy	3m 54s
cargo-deny (advisories, licenses, bans, ...)	2m 36s
rustfmt	23s
cutting a new execution layer	1m 36s
bridge-evm-tests	0s
graphql-rpc	26m 13s
	1h 36m 41s

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