LU-5407 tests: Error message for replay-single 58b and 58c

LU-5407 tests: Error message for replay-single 58b and 58c

In the replay-single test suite, tests 58b and 58c set an attribute,
retrieve the attribute and check that the original message matches
what was set. If large extended attributes is enabled, the attribute
written can be very long. In case of error, we only print the first
few charaters of the message that was set.

Also, call error if there is a problem when the client mounts the
file system on $MOUNT2.

Signed-off-by: James Nunez <james.a.nunez@intel.com>
Change-Id: I8c51ab04d906d74d6eac5a65420203936184ffe4
Reviewed-on: http://review.whamcloud.com/14766
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Cliff White <cliff.white@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>