Added check for HEADLESS_PUBLISH

It should look for AYON_SG_USERNAME even on farm, it shouldn't look for get_local_login

client/ayon_shotgrid/addon.py

@@ -83,7 +83,7 @@ def get_local_storage_key(self):
     def get_credentials(self):
         from .lib import credentials
 
-        if self._client_login_type == "env":
+        if self._client_login_type == "env" or os.getenv("HEADLESS_PUBLISH"):
             user_login = os.getenv("AYON_SG_USERNAME")
             sg_password = None