fix(handlers): use 503 Service Unavailable for DB connection failures

See merge request !777

fix(handlers): do not log when blob or manifest HEAD requests return not found errors

See merge request !786

refactor: use new log package blob descriptor cache

See merge request gitlab-org/container-registry!787

chore(validate): enable validators to enforce reference limits

See merge request gitlab-org/container-registry!788

feat(handlers/configuration): enable enforcing manifest reference limits

See merge request gitlab-org/container-registry!789

feat(handlers): log duration of migration status check

See merge request gitlab-org/container-registry!791

# [3.14.0](gitlab-org/container-registry@v3.13.0-gitlab...v3.14.0-gitlab) (2021-10-28)

### Bug Fixes

* **handlers:** do not log when blob or manifest HEAD requests return not found errors ([0f407e3c](gitlab-org/container-registry@0f407e3c))
* **handlers:** use 503 Service Unavailable for DB connection failures ([fecb78d8](gitlab-org/container-registry@fecb78d8))

### Features

* **handlers:** log when migration status is determined ([75b8230a](gitlab-org/container-registry@75b8230a))
* **handlers/configuration:** enable enforcing manifest reference limits ([2154e730](gitlab-org/container-registry@2154e730))