lint-forge-tests-check-no-build was causing issues in CI because
it was running as part of contracts-bedrock-checks which depends
on contracts-bedrock-build. contracts-bedrock-build builds the
contract files EXCEPT for tests whenever contracts-bedrock has
changed. This means that contracts-bedrock-build would not build
any test files and therefore lint-forge-tests-check-no-build would
not find any test files to check and the job would do nothing.
However, when contracts-bedrock is NOT changed, the build job gets
the full set of artifacts INCLUDING test artifacts from the cache.
This would trigger the full check to actually be run and it would
properly fail.

This PR moves that particular check into contracts-bedrock-tests
so that it's guaranteed to have all of the compiled contracts.