[LOS-1020] Not create updateinfo.xml from updateinfo.db in advisories directory

The updateinfo.xml in advisories directory is not being used. Example:

[root@lxsoftadm29 x86_64]# ls
updateinfo.db  updateinfo.xml
[root@lxsoftadm29 x86_64]# pwd
/mnt/data2/advisories/ALMA9/x86_64

The updateinfo.db is created from the updateinfo.xml files in /$REPO/repodata/. Then the updateinfo.xml in advisories/$DIST/$ARCH is created from updateinfo.db.

Only updateinfo.db is being used in the snapshots projects. Example: https://gitlab.cern.ch/linuxsupport/cronjobs/alma_snapshots/-/blob/master/common/commit-updates-to-docs.sh?ref_type=heads#L63

This MR will not remove the updateinfo.xml from the advisories/$DIST/$ARCH directories - this is something that will be needed to do by hand.