Remove [coordination] check_watchers

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

[1] 46ad2786ae

Related-Bug: #1929178
Change-Id: I8463537ca09db2f0bc443505afaab6a1f9ff5db2

ceilometer/opts.py

@@ -85,14 +85,7 @@ def list_opts():
                 'left empty, per-deployment central agent and per-host '
                 'compute agent won\'t do workload '
                 'partitioning and will only function correctly if a '
-                'single instance of that service is running.'),
-            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'),
+                'single instance of that service is running.')
         ]),
         ('event', ceilometer.event.converter.OPTS),
         ('hardware', itertools.chain(

releasenotes/notes/remove-check_watchers-a7c955703b6d9f57.yaml

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