LU-7667 tests: Write to unique files in $TMP

LU-7667 tests: Write to unique files in $TMP

sanity uses $TMP/files to store the output of 'lfs getstripe'
and does not clean up the $TMP directory. When conf-sanity tries
to create $TMP/files, it fails. These tests need to use a unique
file, $tfile, or directory, $tdir, name in $TMP and should
clean $TMP out before test exits.

Tests should use $TMP instead of /tmp. $TMP defaults to /tmp.

Remove sanity test 51d from the ALWAYS_EXCEPT list.

Signed-off-by: James Nunez <james.a.nunez@intel.com>
Change-Id: I09a0a2be1d88c3f4a0042e3956bbc54f9df61f55
Reviewed-on: http://review.whamcloud.com/18261
Tested-by: Jenkins
Reviewed-by: Wei Liu <wei3.liu@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Saurabh Tandan <saurabh.tandan@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>