fix self reference

Signed-off-by: fbalak <fbalak@redhat.com>

ocs_ci/ocs/resources/mcg.py

@@ -120,7 +120,7 @@ def __init__(self, *args, **kwargs):
             .get("serviceS3")
             .get("internalDNS")[0]
         )
-        self.s3_endpoint = determine_s3_endpoint()
+        self.s3_endpoint = self.determine_s3_endpoint()
         self.mgmt_endpoint = (
             get_noobaa.get("items")[0]
             .get("status")