ObjectStore uploader requires presence of associated `uploads` record
when deleting the upload file (through the carrierwave's after_commit
hook) because we keep info whether file is LOCAL or REMOTE in `upload`
object.
For this reason we can not destroy uploads as "dependent: :destroy" hook
because these would be deleted too soon. Instead we rely on
carrierwave's hook to destroy `uploads` in after_commit hook.
But in before_destroy hook we still have to delete not-mounted uploads
(which don't use carrierwave's destroy hook). This has to be done in
before_Destroy instead of after_commit because `FileUpload` requires
existence of model's object on destroy action.
This is not ideal state of things, in a next step we should investigate
how to unify model dependencies so we can use same workflow for all
uploads.
Related to #45425
This caches the result of Appearance.first in a similar fashion to how
ApplicationSetting instances are cached. We also add some NOT NULL
constraints to the table and correct the timestamp types.
Fixesgitlab-org/gitlab-ce#36066, fixesgitlab-org/gitlab-ce#31698
The only major difference with the EE version is the change from a light and dark logo to only a header logo
The dark logo wasn't used anyway, so it seemed to make sense to me to rename the field to the actual function of it
