Deprecate the "glance-cache-manage" command

Change-Id: I5fe40f1ebd6acd25d4ed2e05d20a409511be08af

glance/cmd/cache_manage.py

@@ -499,6 +499,9 @@ def user_confirm(prompt, default=False):
 
 
 def main():
+    print('In the Caracal development cycle, the glance-cache-manage command '
+          'has been deprecated in favor of the new Cache API. It is scheduled '
+          'to be removed in the Dalmatian development cycle.', file=sys.stderr)
     parser = argparse.ArgumentParser(
         description=_format_command_help(),
         formatter_class=argparse.RawDescriptionHelpFormatter)

releasenotes/notes/deprecate-glance-cache-manage-c88f07d33fcc7ca5.yaml

@@ -0,0 +1,7 @@
+deprecations:
+  - |
+    The ``glance-cache-manage`` command is deprecated in this release in favor
+    of the new Cache API. It is subject to removal at the beginning of the
+    Dalmatian development cycle, following the `OpenStack standard deprecation
+    policy
+    <https://governance.openstack.org/reference/tags/assert_follows-standard-deprecation.html>`_.