Enforce job name length to 255 characters in the database

Problem

Currently, when a user attempts to enter a job name into ci_builds.name that exceeds 255 characters, the page encounters a 500 error. This is because there is a mismatch between what the frontend allows vs what the backend can accommodate. The initial proposal is to implement add a length validation here.

Proposal

It may be worth matching the validation before the next major release of %15.0 so when we incorporate the breaking change, we will have an even higher level of confidence and near-zero risk of enforcing this limit so the HTTP 500 error can't occur. That way, this is fully covered from any possibility of encountering a job length beyond that many characters.