Merge branch '428505-unified-backups-metadata-loading' into 'master'

Unified Backups: Support for loading backup metadata

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/152086



Merged-by: Douglas Barbosa Alexandre <dbalexandre@gmail.com>
Approved-by: Douglas Barbosa Alexandre <dbalexandre@gmail.com>
Reviewed-by: Aakriti Gupta <agupta@gitlab.com>
Co-authored-by: Gabriel Mazetto <gabriel@gitlab.com>
Co-authored-by: Kyle Yetter <kyetter@gitlab.com>