Polling for this status check

Follow up from this comment: #385218 (comment 1211359653)

after retrying the check it will go back into the Pending state, would it be worth adding polling for this status check so it updates once the external validation has run?

The MR widget this is built into has existing functionality we can use to opt-in to polling so it should be pretty straight forward.

We could make it poll for updates always, or to reduce impact on the MR page could start polling once the user clicks Retry