Also check for applications that have exceeded the unsuccessful cap

[JR-G]

Context

We reduced the unsuccessful cap from 20 to 15. It appears that before we did this a candidate managed to exceed 15 and since the logic is only checking for an exact match (on the assumption no one would be able to reach beyond this point) they are getting picked up by our invariant check.

Changes proposed in this pull request

rather than count == cap we will now do count >= cap

Guidance to review

Link to Trello card

Things to check

• If the code removes any existing feature flags, a data migration has also been added to delete the entry from the database
• This code does not rely on migrations in the same Pull Request
• If this code includes a migration adding or changing columns, it also backfills existing records for consistency
• If this code adds a column to the DB, decide whether it needs to be in analytics yml file or analytics blocklist
• API release notes have been updated if necessary
• If it adds a significant user-facing change, is it documented in the CHANGELOG?
• Required environment variables have been updated added to the Azure KeyVault