LU-2559 tests: enable "slow" lustre-rsync tests

LU-2559 tests: enable "slow" lustre-rsync tests

The "SLOW=yes" tests that are disabled in lustre-rsync-test.sh
appear to only be taking about 1-2 minutes each, and are always
passing in the "full" test runs on master.

It won't impact testing throughput significantly to enable them
even for review builds.  It increases overall test time by about
10 minutes in total, but improves our test coverage noticeably.

Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Change-Id: Iccec870c8b0936aa9e4532da6e8bde2d991ccab0
Reviewed-on: http://review.whamcloud.com/5214
Reviewed-by: Jian Yu <jian.yu@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: wangdi <di.wang@intel.com>
Reviewed-by: Keith Mannthey <keith.mannthey@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>