Revert "Fix todo that is not needed anymore stestr conf"

This reverts commit 35d94fd609.

Removing the try except makes tempest not stable branch invariant and break backports.
this fixes that

Change-Id: Ib78ca25ff25addd4c19716e59f6e638dabdc7054

.stestr.conf

@@ -1,3 +1,3 @@
 [DEFAULT]
-test_path=mistral_tempest_tests
+test_path=./mistral-tempest-plugin/tests
 top_dir=./

mistral_tempest_tests/services/base.py

@@ -81,11 +81,16 @@ class MistralClientBase(rest_client.RestClient):
 
     def delete_obj(self, obj, name, force=None):
         if force:
-            return self.delete('{obj}/{name}?force={force}'.format(
-                obj=obj,
-                name=name,
-                force=bool(force))
-            )
+            # TODO(apetrich) This try except is a partial implementation
+            # to be removed once force deletion lands in mistral
+            try:
+                return self.delete('{obj}/{name}?force={force}'.format(
+                    obj=obj,
+                    name=name,
+                    force=bool(force))
+                )
+            except Exception:
+                pass
 
         return self.delete('{obj}/{name}'.format(obj=obj, name=name))