Three guards have been added:
1. The service used by the worker will not raise an error
upon receiving an invalid regex but it will return an error
response
2. The expiration container policy will not schedule the
next run for the given container expiration policy if it is
valid. In addition, the given container expiration policy
will be disabled
3. Added a new UntrustedRegexp validator for Grape APIs.
This one has been used in `API::ProjectContainerRepositories` to prevent
enqueuing a job with invalid regex