Default innodb_file_per_table=OFF for S3 as that shard has many more
tables than the others (OFF reduces file handle usage, among other
things).

Default innodb_file_per_table=ON for S4 (commons), which is the only
shard that hasn't had that applied previously. Slaves will migrate
gradually (requires rolling reload or xtrabackup clone). Commons is
one shard that would benefit from InnoDB barracuda compression on some
slave/table combinations.

Change-Id: I624199606a4f4633716c47c36f1c98de14b2b2b9