TECH DEBT Use right workspace api call for listing credentials (#3957)

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Resolves #3571

Author: HariGS-DB

src/databricks/labs/ucx/aws/credentials.py

@@ -59,9 +59,8 @@ def list(self, include_names: set[str] | None = None) -> set[str]:
 
     def list_glue(self) -> dict[str, str]:
         # list existed service credentials that are using iam roles, capturing the arns and names
-        # TODO: replace with SDK call when available
         try:
-            credential_response = self._ws.api_client.do('GET', '/api/2.1/unity-catalog/credentials')
+            credential_response = self._ws.credentials.list_credentials()
         except NotFound:
             logger.info('Could not retrieve credentials for Glue access. ')
             return {}