cephadm: change tests to assert using mock call not func.args

cephadm: change tests to assert using mock call not func.args

The Python docs [1] note that:
  Changed in version 3.8: Added args and kwargs properties.

In order to run tests on python 3.6 (example: `tox -e py36`) we
change the tests to do the asserts using the older call(...)
comparison style, with mock.ANY used for args we don't care about.

[1] - https://docs.python.org/3/library/unittest.mock.html#unittest.mock.Mock.call_args

Signed-off-by: John Mulligan <jmulligan@redhat.com>