dbscripts: Remove obsolete integrity-check.{service,timer}

They haven't been used for over 7 years[1] and was just removed from
dbscripts[2][3].

[1] bcd20f65 ("Disable the integrity check timer and service.")
[2] dbscripts!58
[3] f354ae35 ("dbscripts: Bump to latest commit for repos/archive split fixes")

roles/dbscripts/files/integrity-check.service

-[Unit]
-Description=Integrity Check
-
-[Service]
-Type=oneshot
-User=git-packages
-ExecStart=/srv/repos/git-packages/dbscripts/cron-jobs/integrity-check arch-notifications@archlinux.org,arch-dev-public@archlinux.org

roles/dbscripts/files/integrity-check.timer

-[Unit]
-Description=Integrity Check
-
-[Timer]
-OnCalendar=weekly
-Persistent=true
-
-[Install]
-WantedBy=timers.target