Remove [coordination] check_watchers

This parameter has had no effect for several cycles and was officially
deprecated during Xena cycle[1].

[1] 082d67f5965c69ee72be4bb1e1c44fd9ff5526d5

Related-Bug: #1929178
Change-Id: Ifeda4499b46129bf81f10286f38fff409c93f907

aodh/coordination.py

@@ -37,12 +37,6 @@ OPTS = [
                  deprecated_name='heartbeat',
                  help='Number of seconds between heartbeats for distributed '
                       'coordination.'),
-    cfg.FloatOpt('check_watchers',
-                 default=10.0,
-                 deprecated_for_removal=True,
-                 deprecated_reason='This parameter is no longer used.',
-                 help='Number of seconds between checks to see if group '
-                      'membership has changed'),
     cfg.IntOpt('retry_backoff',
                default=1,
                help='Retry backoff factor when retrying to connect with'

releasenotes/notes/remove-check_watchers-df14cecc258a3510.yaml

@@ -0,0 +1,4 @@
+---
+upgrade:
+  - |
+    The ``[coordination] check_watchers`` parameter has been removed.