Add basic auth to content removal test

We were getting failed tests on ContentUnitRemoveTestCase because
the delete was being made by the requests library client without
any any credentials.

Then, we would get 403 (forbidden) instead of 405 (method now allowed).

This assumes the delete requires auth in the first place.

Backported from: bc957d1

pulp_rpm/tests/functional/api/test_crud_content_unit.py

@@ -173,9 +173,10 @@ def do_test_remove_unit(self, remote_url):
         repo_content = get_content(repo.to_dict())
         base_addr = self.cfg.get_host_settings()[0]["url"]
 
+        basic_auth = requests.auth.HTTPBasicAuth("admin", "password")
         for content_type in repo_content.keys():
             response = requests.delete(
-                urljoin(base_addr, repo_content[content_type][0]["pulp_href"])
+                urljoin(base_addr, repo_content[content_type][0]["pulp_href"]), auth=basic_auth
             )
             self.assertEqual(response.status_code, 405)