[CI] Fix unpacking in premerge advisor upload (#163944)

Seems like the function returns a dict, not a list of tuples like the
other.
Not sure of the schema or the design for this, so fixing the code
without using the test-suite name. But this might have to be addressed
once the owner can take a look.

.ci/premerge_advisor_upload.py

@@ -32,8 +32,11 @@ def main(commit_sha, workflow_run_number, build_log_files):
         "platform": current_platform,
     }
     if test_failures:
-        for name, failure_message in test_failures:
-            failure_info["failures"].append({"name": name, "message": failure_message})
+        for _, failures in test_failures.items():
+            for name, failure_message in failures:
+                failure_info["failures"].append(
+                    {"name": name, "message": failure_message}
+                )
     else:
         ninja_failures = generate_test_report_lib.find_failure_in_ninja_logs(ninja_logs)
         for name, failure_message in ninja_failures: