Modify MBS to use a separate Kerberos context per thread so both threads can use the thread keyring to store the Kerberos cache

This commit includes the backport of the changes to `krb_login` in
https://pagure.io/koji/pull-request/1187. This change is required
for our separate threads to use a separate Kerberos context per thread.

tests/test_views/test_views.py

@@ -417,7 +417,7 @@ class TestViews:
                 for key, part in zip(nsvc_keys, nsvc_parts):
                     assert item[key] == part
 
-    @patch("koji.ClientSession")
+    @patch("module_build_service.builder.KojiModuleBuilder.KojiClientSession")
     def test_query_builds_with_binary_rpm(self, ClientSession):
         """
         Test for querying MBS with the binary rpm filename. MBS should return all the modules,