Remove Support for "Blank" value on Maximum Allowable Lifetime for PATs

Background

In %16.0 we are making all access tokens have an expiry date. We will no longer support non-expiring access tokens.

Currently, there is a setting which an admin can leave blank that allows "no limit" for max token expiry. We need to revise this.

Proposal

1. Remove ability to leave this blank. Revise it to state that it applies to all types of access tokens, not just personal - see comment

2. Enforce a maximum lifetime of 365 days from current date.

Availability & Testing

Ensure e2e-package-and-test-ee job passes