Description of problem:
Test "test_default_share_group_type_applied" is failed with code 404 that because 
there is a wrong skip condition. The test runs when "default_share_type_name" 
configuration option is defined but that does not mean that group share type also 
exists.
So in case there is a default share type but not a group share type the api call 
for default share group types fails because resource could not be found.

Version-Release number of selected component (if applicable):
puppet-manila-15.4.1-0.20200403160104.e41b1b6.el8ost.noarch
python3-manilaclient-1.29.0-0.20200310223441.1b2cafb.el8ost.noarch

How reproducible:
100%

Steps to Reproduce:
1. Deploy OSP16.1.1
2. Run "test_default_share_group_type_applied" test

Actual results:
Test fails with code 404 because default group type is not found

Expected results:
We should skip the test in case there is not a default group type

Traceback (most recent call last):
  File "/home/stack/tempest-auto/.venv/lib/python3.6/site-packages/ddt.py", line 182, in wrapper
    return func(self, *args, **kwargs)
  File "/home/stack/tempest-auto/manila-tempest-plugin/manila_tempest_tests/tests/api/admin/test_share_groups.py", line 141, in test_default_share_group_type_applied
    version=version
  File "/home/stack/tempest-auto/manila-tempest-plugin/manila_tempest_tests/services/share/v2/json/shares_client.py", line 1254, in get_default_share_group_type
    extra_headers=extra_headers, version=version)
  File "/home/stack/tempest-auto/manila-tempest-plugin/manila_tempest_tests/services/share/v2/json/shares_client.py", line 78, in get
    resp, body = super(SharesV2Client, self).get(url, headers=headers)
  File "/home/stack/tempest-auto/tempest/tempest/lib/common/rest_client.py", line 313, in get
    return self.request('GET', url, extra_headers, headers)
  File "/home/stack/tempest-auto/tempest/tempest/lib/common/rest_client.py", line 702, in request
    self._error_checker(resp, resp_body)
  File "/home/stack/tempest-auto/tempest/tempest/lib/common/rest_client.py", line 808, in _error_checker
    raise exceptions.NotFound(resp_body, resp=resp)
tempest.lib.exceptions.NotFound: Object not found
Details: {'code': 404, 'message': 'Default share group type not found.'}