Property name 'user_config_flags' used more than once

[Corey Bryant]

There are 2 bugs in the masakari-monitors user flags support:

1) They aren't put in the [DEFAULT] section (they're put in the [api] section)

2) Unit tests have started failing as shown below. This is new since charms.openstack gained support for config flags:
https://github.com/openstack/charms.openstack/commit/d049eee8f47e3913123762b6cd4f493e8ff0d18d
https://github.com/openstack/charms.openstack/commit/18ac668cd78e16adba5706e4d9606ff3f15ddd6e

==============================
Failed 2 tests - output below:
==============================

unittest.loader._FailedTest.unit_tests.test_lib_charm_openstack_masakari_monitors
---------------------------------------------------------------------------------

Captured traceback:
~~~~~~~~~~~~~~~~~~~
    ImportError: Failed to import test module: unit_tests.test_lib_charm_openstack_masakari_monitors
Traceback (most recent call last):
  File "/usr/lib/python3.8/unittest/loader.py", line 436, in _find_test_path
    module = self._get_module_from_name(name)
  File "/usr/lib/python3.8/unittest/loader.py", line 377, in _get_module_from_name
    __import__(name)
  File "/mnt/release-tools/charms/masakari-monitors/unit_tests/test_lib_charm_openstack_masakari_monitors.py", line 19, in <module>
    import charm.openstack.masakari_monitors as masakari_monitors
  File "/mnt/release-tools/charms/masakari-monitors/src/lib/charm/openstack/masakari_monitors.py", line 16, in <module>
    class MasakariMonitorsCharm(charms_openstack.charm.OpenStackCharm):
  File "/mnt/release-tools/charms/masakari-monitors/src/lib/charm/openstack/masakari_monitors.py", line 65, in MasakariMonitorsCharm
    def user_config_flags(self):
  File "/mnt/release-tools/charms/masakari-monitors/.tox/py38/lib/python3.8/site-packages/charms_openstack/adapters.py", line 81, in config_property
    raise RuntimeError(
RuntimeError: Property name 'user_config_flags' used more than once for configuration?

unittest.loader._FailedTest.unit_tests.test_masakari_monitors_handlers
----------------------------------------------------------------------

Captured traceback:
~~~~~~~~~~~~~~~~~~~
    ImportError: Failed to import test module: unit_tests.test_masakari_monitors_handlers
Traceback (most recent call last):
  File "/usr/lib/python3.8/unittest/loader.py", line 436, in _find_test_path
    module = self._get_module_from_name(name)
  File "/usr/lib/python3.8/unittest/loader.py", line 377, in _get_module_from_name
    __import__(name)
  File "/mnt/release-tools/charms/masakari-monitors/unit_tests/test_masakari_monitors_handlers.py", line 17, in <module>
    import reactive.masakari_monitors_handlers as handlers
  File "/mnt/release-tools/charms/masakari-monitors/src/reactive/masakari_monitors_handlers.py", line 19, in <module>
    import charm.openstack.masakari_monitors as masakari_monitors # noqa
  File "/mnt/release-tools/charms/masakari-monitors/src/lib/charm/openstack/masakari_monitors.py", line 8, in <module>
    charms_openstack.charm.use_defaults('charm.default-select-release')
  File "/mnt/release-tools/charms/masakari-monitors/.tox/py38/lib/python3.8/site-packages/charms_openstack/charm/defaults.py", line 44, in use_defaults
    _default_handler_map[state]()
  File "/mnt/release-tools/charms/masakari-monitors/.tox/py38/lib/python3.8/site-packages/charms_openstack/charm/defaults.py", line 92, in make_default_select_release_handler
    def default_select_release():
  File "/mnt/release-tools/charms/masakari-monitors/.tox/py38/lib/python3.8/site-packages/charms_openstack/charm/core.py", line 190, in register_os_release_selector
    raise RuntimeError(
RuntimeError: Only a single release_selector_function is supported. Called with default_select_release

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/charm-masakari-monitors/+/853657

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/charm-masakari-monitors/+/853657
Committed: https://opendev.org/openstack/charm-masakari-monitors/commit/e7fd6815c902604970b8069409cfcc0113dc33f3
Submitter: "Zuul (22348)"
Branch: master

commit e7fd6815c902604970b8069409cfcc0113dc33f3
Author: Corey Bryant <email address hidden>
Date: Wed Oct 12 13:10:11 2022 +0000

    Fix config-flags support

    This change puts the specified key/value config-flags into
    the [DEFAULT] section of the config file rather than the [api]
    section, as they were supposed to be in the [DEFAULT] section.

    Additionally, this change switches to using the config-flags
    support from charms.openstack.

    Closes-Bug: #1986943
    Change-Id: I77a35c074e234c3bdfa78800b05ee770492e0694

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/zed
Review: https://review.opendev.org/c/openstack/charm-masakari-monitors/+/875896