python-common: handle "anonymous_access: false" in to_json of Grafana spec

python-common: handle "anonymous_access: false" in to_json of Grafana spec

This option is dropped during the regular ServiceSpec to_json
function, as it is not equipped to handle booleans that default
to True. In hindsight, we just shouldn't have added a boolean
field that defaults to True, but it's a bit late now to change
the attribute, so this implements a workaround.

NOTE: if OrderedDict[str, Any] is not encapsulated in quotes,
a bunch of mgr modules fail to load on python 3.6 with

mgr[py] Traceback (most recent call last):
 File "/usr/share/ceph/mgr/volumes/__init__.py", line 2, in <module>
   from .module import Module
 File "/usr/share/ceph/mgr/volumes/module.py", line 7, in <module>
   import orchestrator
 File "/usr/share/ceph/mgr/orchestrator/__init__.py", line 3, in <module>
   from .module import OrchestratorCli
 File "/usr/share/ceph/mgr/orchestrator/module.py", line 19, in <module>
   from ceph.deployment.drive_group import DriveGroupSpec, DeviceSelection, OSDMethod
 File "/lib/python3.6/site-packages/ceph/deployment/drive_group.py", line 5, in <module>
   from ceph.deployment.service_spec import (
 File "/lib/python3.6/site-packages/ceph/deployment/service_spec.py", line 1986, in <module>
   class GrafanaSpec(MonitoringSpec):
 File "/lib/python3.6/site-packages/ceph/deployment/service_spec.py", line 2034, in GrafanaSpec
   def to_json(self) -> OrderedDict[str, Any]:
TypeError: 'type' object is not subscriptable

Fixes: https://tracker.ceph.com/issues/65511
Signed-off-by: Adam King <adking@redhat.com>
(cherry picked from commit 0089536567b2ce8d3215339b264a48de06bfac38)