common: Check the file system consistency on SCRATCH_DEV

There are about 198 tests which requires scratch_dev, but does not check
the file system consistency afterwards. Xfstests infrastructure does not
do it automatically, so fix it by running _check_scratch_fs() after
each test that _require_scratch.

Also remove all the _check_scratch_fs() calls that are not actually needed
and will be covered by the check script.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

tests/xfs/034

@@ -83,8 +83,6 @@ then
 fi
 
 # pv 801241 causes corruption here (inode left in agi_unlinked list)
-_check_scratch_fs
-
 echo "*** done"
 # happy exit
 status=0