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/generic/312

@@ -67,6 +67,5 @@ echo "Silence is golden"
 $XFS_IO_PROG -f -c "falloc 0 6g" $SCRATCH_MNT/testfile.$seq >>$seqres.full 2>&1
 
 _scratch_unmount
-_check_scratch_fs
 status=0
 exit