Log auditing tries to write to the database in read-only mode

Currently there are only sparse checks in Quay to determine whether the registry is in read-only mode and if failed audit log writes to the database should be ignored. This is because up until PROJQUAY-2344 and PROJQUAY-5411 audit log events were mostly triggered solely on API endpoints that were gated for read-only mode. Authentication in particular is not gated on read-only mode and will therefore cause log audit events to attempt to be written, and cause failures if the database is in read-only mode.