Taskflow doesn't treat boolean configuration properly

At the moment taskflow just tries to load the configuration with getting attribute from passed config and assuming it's boolean:
https://opendev.org/openstack/taskflow/src/commit/5bcac4c7d4503be8161bcf159981199e3ea89d4d/taskflow/jobs/backends/impl_zookeeper.py#L832

In fact, at least octavia does pass variables as str and not as bool.

So in case in octavia.conf you will define following:

[task_flow]
jobboard_zookeeper_ssl_options = use_ssl:True,verify_certs:False,check_compatible:False

taskflow will end up with wrong behaviour. Since type(self._conf['check_compatible']) is str, condition `if self._conf.get('check_compatible', True)` will be treated as true no matter value you place, as non-empty string will always be evaluated as True.

While with use_ssl it's not _that_ critical as default value is False, so to disable you can simply skip defining the variable, for verify_certs and check_compatible things are way worse.