Merge pull request #29478 from michael-redpanda/gbac/core-15351-flaky-gbac

CORE-15351: Deflake upgrade gbac test

Author: michael-redpanda

src/v/kafka/server/server.cc

@@ -2061,7 +2061,11 @@ ss::future<response_ptr> create_acls_handler::handle(
                     error_code::invalid_config, "GBAC feature not yet active");
               } else {
                   response.data.results.emplace_back(
-                    map_topic_error_code(results[i]));
+                    map_topic_error_code(results[i]),
+                    results[i] == cluster::errc::success
+                      ? std::nullopt
+                      : std::make_optional<ss::sstring>(
+                          fmt::format("{}", results[i])));
               }
           },
           [&response](creatable_acl_result r) {

tests/rptest/tests/acls_test.py

@@ -724,11 +724,16 @@ def test_upgrade_gbac(self):
         acl_input.operation = ["all"]
         acl_input.cluster = True
 
-        result = self.get_super_client().acl_create(acl=acl_input)
-        self.logger.debug(f"Result: {result}")
+        def wait_for_gbac_feature_response():
+            result = self.get_super_client().acl_create(acl=acl_input)
+            self.logger.debug(f"result: {result}")
+            return "INVALID_CONFIG: GBAC feature not yet active" in result
 
-        assert "INVALID_CONFIG: GBAC feature not yet active" in result, (
-            f"Unexpected result: {result}"
+        wait_until(
+            wait_for_gbac_feature_response,
+            timeout_sec=30,
+            backoff_sec=1,
+            err_msg="Timed out waiting for GBAC feature response",
         )
 
         # Upgrade remaining nodes