multi policy: Fix logging issues with multiple policies

This patchset mostly aims to fix logging issues surrounding
multiple policies introduced by [0]. Some of the LOG messages
still only log `rule` arg when they should log all the `rules`
arg instead to capture all the policies being enforced.

In addition, this patchset:

* corrects docstring formatting with rbac_rule_validation following [1]
* changes unit tests in test_rbac_rule_validation to test non-deprecated
  arg `rules` instead of `rule` (tests also exist for ensuring that
  `rule` is handled correctly until it is finally removed from code)
* rewords some log messages to better conform to multi policy support

[0] https://review.openstack.org/#/c/554764/
[1] https://review.openstack.org/#/c/570262/

Partially Implements: bp rbac-testing-multiple-policies
Story: 2002620
Task: 22250

Change-Id: I3df69d5a476416378bde14ee6a258ff5ed40e363
2 files changed