Avoid ci-management archiving files twice

Avoid ci-management archiving files twice

This is a follow-up to https://gerrit.fd.io/r/c/csit/+/20394

https://gerrit.fd.io/r/20119
has changed the way archival works,
everything should now go to logs.fd.io
(instead of appearing on run page in jenkins.fd.io).

The glob pattern for archiving is quite eager,
doing recursive search. That is good, as it can find
also misplaced useful outputs.
But it also means our usage of copy_archives function
creates two copies of archived directtories,
usually archives/ and archives/archive/.

This change renames copy_archives to move_archives,
with few workarounds to support multiple calls.

I also renamed ARCHIVE_DIR value from $CSIT_DIR/archive
to $CSIT_DIR/archives to make "move" operation look natural.

Finally, download_builds function is being removed,
as after recent improvements to VPP compilation speed
nobody seems to be using it.

Change-Id: I19a429e1dfdfaab7fcf32a9609963b1aebd33c6c
Signed-off-by: Vratko Polak <vrpolak@cisco.com>