Fix skip condition for "test_default_share_group_type_applied"

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.
This patch skips the test in case group share type is not found.

Change-Id: I7e16b341e3c9d76647eb2fa08909392328fb330b
diff --git a/manila_tempest_tests/tests/api/admin/test_share_groups.py b/manila_tempest_tests/tests/api/admin/test_share_groups.py
index c7b3a42..541acbb 100644
--- a/manila_tempest_tests/tests/api/admin/test_share_groups.py
+++ b/manila_tempest_tests/tests/api/admin/test_share_groups.py
@@ -16,6 +16,7 @@
 import ddt
 from tempest import config
 from tempest.lib.common.utils import data_utils
+from tempest.lib import exceptions
 import testtools
 from testtools import testcase as tc
 
@@ -136,10 +137,13 @@
               constants.SHARE_GROUPS_GRADUATION_VERSION, LATEST_MICROVERSION]))
     def test_default_share_group_type_applied(self, version):
         self.skip_if_microversion_not_supported(version)
-
-        default_type = self.shares_v2_client.get_default_share_group_type(
-            version=version
-        )
+        try:
+            default_type = self.shares_v2_client.get_default_share_group_type(
+                version=version
+            )
+        except exceptions.NotFound:
+            msg = "There is no default share group type"
+            raise self.skipException(msg)
         default_share_types = default_type['share_types']
 
         share_group = self.create_share_group(