housekeep: remove "setup-repo" command and "pkgmaint" script

setup-repo

Marked as deprecated about 6 years ago.
Time to bury it.

Issue report: #428 (closed)

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pkgmaint

With the removal of the "setup-repo" command this script becomes obsolete, because it is not possible to reserve a repo anymore.
Hence we don't need cleanup.

We've also seen issues in case the last packager's user account is removed, leading to the deletion of a Package.

Issue report: #425 (closed)

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"Last packager"

Data for packages that do not have a "Last Packager"
(e.g. because the user account was deleted)
should still be available from the /rpc and metadata archives.

Signed-off-by: moson-mo mo-son@mailbox.org