phase1: set rsync timeouts

phase1: set rsync timeouts

Regardless of the timeout settings of buildbot or the use of 'pv' to
circumvent them, it is desirable to ensure that rsync will fail if the
connection hangs or cannot be established for any reason.

Otherwise, we might end up with builders stuck on network transfers.

This commit sets data transfer timeout to 120s and connection timeout
to 20s.

Signed-off-by: Thibaut VARÈNE <[email protected]>