Replace watcherclient functional job with python-watcherclient-functional

https://review.opendev.org/c/openstack/python-watcherclient/+/943132
Move functional tests from watcher_tempest_plugin to watcherclient and
adds new zuul job based on devstack-tox-functional to run functional tests.

This pr replaces the existing zuul job using tempest regex with
devstack tox functional job. The new job will run only watcher/api
changes.

Closes-Bug: #2100741

Depends-On: https://review.opendev.org/c/openstack/python-watcherclient/+/943132

Change-Id: Ic2371745fe8aaf6f283151111fec4f92ea6bdf69
Signed-off-by: Chandan Kumar (raukadah) <chkumar@redhat.com>

.zuul.yaml

@@ -13,7 +13,9 @@
         - watcher-grenade
         - watcher-tempest-strategies
         - watcher-tempest-actuator
-        - watcherclient-tempest-functional
+        - python-watcherclient-functional:
+            files:
+              - ^watcher/api/*
         - watcher-tempest-functional-ipv6-only
         - watcher-prometheus-integration
     gate:
@@ -158,15 +160,6 @@
       - ^tools/.*$
       - ^tox.ini$
 
-- job:
-    # This job is used in python-watcherclient repo
-    name: watcherclient-tempest-functional
-    parent: watcher-tempest-functional
-    timeout: 4200
-    vars:
-      tempest_concurrency: 1
-      tempest_test_regex: watcher_tempest_plugin.tests.client_functional
-
 - job:
     name: watcher-sg-core-tempest-base
     parent: devstack-tempest