We have awaitable_hello_fcv_change.js and rollback_set_fcv.js but no test that tests that FCV changes during rollback also will unblock and reply to waiting hello requests.

In these cases:

• - the FCV document is rolled back from fully upgraded to upgrading
• - the FCV document is rolled back from upgrading to fully downgraded
• - the FCV document is rolled back from fully downgraded to isCleaningServerMetadata
• - the FCV document is rolled back from downgrading to fully upgraded
  this should unblock/reply to waiting hello requests

but when the FCV document is rolled back from isCleaningServerMetadata to downgrading this should not unblock/reply to waiting hello requests