The default configuration was changed to use the advanced cache pool in
keystonemiddleware 9.3.0 (Xena release) [1].

This reverts commit 5a52d8e4 (except the
release note).

[1] https://review.opendev.org/c/openstack/keystonemiddleware/+/773939

Change-Id: I290d0a81c57c189b6eb62fc3eee3ed19f441671b