This reverts commit 3f7e74ab24.
After identifying how to workaround the performance issues on the
undercloud, let's put this back in. Enabling innodb_file_per_table is
important for operators to be able to better manage their databases.
Change-Id: I435de381a0f0e3ef221e498f442335cdce3fb818
Depends-On: I77507c638237072e38d9888aff3da884aeff0b59
Closes-Bug: #1660722