fstests: rename _scratch_inject_logprint to _scratch_remount_dump_log

fstests: rename _scratch_inject_logprint to _scratch_remount_dump_log

Rename _scratch_inject_logprint to _scratch_remount_dump_log to
better describe what this function does. _scratch_remount_dump_log
unmounts and remounts the scratch device, dumping the log.

Signed-off-by: Catherine Hoang <catherine.hoang@oracle.com>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>