Fix get_mon_map() for octopus and later

The "ceph mon_status" command seems to have disappeared on octopus and
later, and is replaced by "ceph quorum_status". This changes the
get_mon_map() function to detect the underlying ceph version and do the
right thing.

Note that the fix is actually in charm-helpers, and this has been
manually synced into the charm [1].

Note: also picked pyparsing pin to allow tests to run.

Cherry-picked from master.

[1] https://github.com/juju/charm-helpers/pull/659

Change-Id: I59cf6fc19cf2a91b0aef37059cdb0ed37379b5cb
Closes-Bug: #1951094

hooks/charmhelpers/contrib/storage/linux/ceph.py

@@ -813,8 +813,10 @@ def get_mon_map(service):
              ceph command fails.
     """
     try:
+        octopus_or_later = cmp_pkgrevno('ceph-common', '15.0.0') >= 0
+        mon_status_cmd = 'quorum_status' if octopus_or_later else 'mon_status'
         mon_status = check_output(['ceph', '--id', service,
-                                   'mon_status', '--format=json'])
+                                   mon_status_cmd, '--format=json'])
         if six.PY3:
             mon_status = mon_status.decode('UTF-8')
         try:

test-requirements.txt

@@ -7,6 +7,7 @@
 #       requirements.  They are intertwined.  Also, Zaza itself should specify
 #       all of its own requirements and if it doesn't, fix it there.
 #
+pyparsing<3.0.0  # aodhclient is pinned in zaza and needs pyparsing < 3.0.0, but cffi also needs it, so pin here.
 cffi==1.14.6; python_version < '3.6'  # cffi 1.15.0 drops support for py35.
 setuptools<50.0.0  # https://github.com/pypa/setuptools/commit/04e3df22df840c6bb244e9b27bc56750c44b7c85