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

Change-Id: I70e7a9edc705c57232b217d893fe28068e99b505
Reviewed-on: http://review.couchbase.org/41462
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>