MB-6972:  remove 32-bit DEB packages from workflow

Change-Id: I3e6eede5c9b23beebcafe2181dd54b0b56c0283f
Reviewed-on: http://review.couchbase.org/41510
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>