EX-2860 pcc: test interoperability with 2.14.0

EX-2860 pcc: test interoperability with 2.14.0

For Lustre 2.14.0 servers, it fails many of subtests that are
PCC-RO specific.
In this patch, each subtest related to PCC-RO adds an connect
flag check and skip it when run against old servers without
PCC-RO support.

Test-Parameters: serverversion=2.14 testlist=sanity-pcc
Signed-off-by: Qian Yingjin <qian@ddn.com>
Change-Id: Ie4fc41b2dc51a038027009fbcc6e86f9d61cd54f
Reviewed-on: https://review.whamcloud.com/43104
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Nunez <jnunez@whamcloud.com>
Reviewed-by: Li Xi <lixi@ddn.com>