Prepare tempest-slow-parallel job and run periodically

tempest-slow-py3 job run all the slow test serially which
takes lot of time and end up job timeout. This preparing
tempest-slow-parallel job which will run slow tests parallelly
in periodic run. Based on the results, later we can make
tempest-slow-py3 job to run tests in parallel.

Also, run tempest-full-parallel in periodic and based on the
result we can run tempest-full-py3 job scenario tests in parallel.

Relavant-Bug: #2004780

Change-Id: I876dacb40daa384cddc8faae3200cd3d39506ddc

tox.ini

@@ -289,6 +289,18 @@ commands =
     find . -type f -name "*.pyc" -delete
     tempest run --serial --regex {[testenv:slow-serial]regex} {posargs}
 
+[testenv:slow]
+envdir = .tox/tempest
+sitepackages = {[tempestenv]sitepackages}
+basepython = {[tempestenv]basepython}
+setenv = {[tempestenv]setenv}
+deps = {[tempestenv]deps}
+# The regex below is used to select the slow tagged tests:
+regex = '\[.*\bslow\b.*\]'
+commands =
+    find . -type f -name "*.pyc" -delete
+    tempest run --regex {[testenv:slow]regex} {posargs}
+
 [testenv:ipv6-only]
 envdir = .tox/tempest
 sitepackages = {[tempestenv]sitepackages}

zuul.d/integrated-gate.yaml

@@ -293,6 +293,13 @@
     branches: ^(?!stable/(ocata|pike|queens|rocky|stein|train)).*$
     vars: *tempest_slow_vars
 
+- job:
+    name: tempest-slow-parallel
+    parent: tempest-slow-py3
+    # This job run slow tests in parallel.
+    vars:
+      tox_envlist: slow
+
 - job:
     name: tempest-cinder-v2-api
     parent: devstack-tempest

zuul.d/project.yaml

@@ -11,7 +11,7 @@
         - openstack-tox-py38
         - openstack-tox-py39
         - openstack-tox-py310
-        - tempest-full-parallel:
+        - tempest-full-py3:
             # Define list of irrelevant files to use everywhere else
             irrelevant-files: &tempest-irrelevant-files
               - ^.*\.rst$
@@ -26,8 +26,6 @@
               - ^.gitignore$
               - ^.gitreview$
               - ^.mailmap$
-        - tempest-full-py3:
-            irrelevant-files: *tempest-irrelevant-files
         - tempest-full-ubuntu-focal:
             irrelevant-files: *tempest-irrelevant-files
         - glance-multistore-cinder-import:
@@ -182,6 +180,8 @@
     periodic:
       jobs:
         - tempest-all
+        - tempest-slow-parallel
+        - tempest-full-parallel
         - tempest-full-oslo-master
         - tempest-stestr-master
         - tempest-full-py3-ipv6

zuul.d/tempest-specific.yaml

@@ -34,7 +34,6 @@
 - job:
     name: tempest-full-parallel
     parent: tempest-full-py3
-    voting: false
     branches:
       - master
     description: |