Secure Files are not included in backup

A customer (ZD internal link) who is using Project Secure Files has recently found that the contents of /var/opt/gitlab/gitlab-rails/shared/ci_secure_files is not included in the backup file produced by the gitlab-backup utility.

This means if the system needed to be restored from backup the contents of uploaded Secure Files would be lost. Which could cause significant problems for projects configured to use them, and block builds.

For reference the backup currently contains the following tarballs of locally stored files:

-rw------- git/git       19045 2023-05-16 05:44 uploads.tar.gz
-rw------- git/git         230 2023-05-16 05:44 builds.tar.gz
-rw------- git/git      713727 2023-05-16 05:44 artifacts.tar.gz
-rw------- git/git         154 2023-05-16 05:44 pages.tar.gz
-rw------- git/git      776582 2023-05-16 05:44 lfs.tar.gz
-rw------- git/git         147 2023-05-16 05:44 terraform_state.tar.gz
-rw------- git/git   124939822 2023-05-16 05:44 registry.tar.gz
-rw------- git/git         147 2023-05-16 05:44 packages.tar.gz