Split protection unit tests into its own job

There are so many protection tests now, and for the moment they are so
inefficient, that running them all as part of our main unit test suite
for py27, py36, py37, and cover jobs yields a high rate of timeouts
which reduces our own development velocity and negatively impacts every
project that co-gates with keystone. This change splits the protection
tests into their own level of tests outside of the configured stestr
test_path and adds a separate tox environment and zuul job to run just
the protection tests on their own. Parallelizing these tests should help
alleviate the timeout issue while we work on making these tests more
efficient.

Change-Id: Ibb12053bd6864a153f7e3998dbd008b6eec4295b

.zuul.yaml

@@ -68,6 +68,14 @@
       tox_env: upgrade
       osa_test_repo: openstack/openstack-ansible-os_keystone
 
+- job:
+     name: keystone-tox-protection
+     parent: openstack-tox-py37
+     vars:
+       tox_envlist: protection
+       bindep_profile: test py37
+       python_version: 3.7
+
 # Experimental
 - job:
     name: keystone-tox-patch_cover
@@ -211,6 +219,7 @@
             irrelevant-files: *tempest-irrelevant-files
         - tempest-ipv6-only:
             irrelevant-files: *tempest-irrelevant-files
+        - keystone-tox-protection
     gate:
       jobs:
         # Override tox timeouts
@@ -236,6 +245,7 @@
             irrelevant-files: *tempest-irrelevant-files
         - tempest-ipv6-only:
             irrelevant-files: *tempest-irrelevant-files
+        - keystone-tox-protection
     experimental:
       jobs:
         - keystone-tox-patch_cover

tox.ini

@@ -1,7 +1,7 @@
 [tox]
 minversion = 2.5.0
 skipsdist = True
-envlist = py27,py37,pep8,api-ref,docs,genconfig,genpolicy,releasenotes
+envlist = py27,py37,pep8,api-ref,docs,genconfig,genpolicy,releasenotes,protection
 
 [testenv]
 usedevelop = True
@@ -196,3 +196,9 @@ deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt
   .[ldap,memcache,mongodb]
+
+[testenv:protection]
+basepython = python3
+commands =
+  find keystone -type f -name "*.pyc" -delete
+  stestr run --test-path=./keystone/tests/protection {posargs}