Today the `ReservedClusterStateService` decides whether or not to submit an update-error task depending on the content of the last-applied state as exposed by `ClusterService#state()`. This may happen concurrently with another state being published, so does not give a fully consistent view of the latest state. Instead it should check the state within the cluster state task executor, triggering a no-op update as appropriate.
server/src/test/java/org/elasticsearch/reservedstate/service/ReservedClusterStateServiceTests.java
"state": {
                     "cluster_settings": {
                         "indices.recovery.max_bytes_per_sec": "50mb"
                 }
            }
            """;
        AtomicReference<Exception> x = new AtomicReference<>();
        try (XContentParser parser = XContentType.JSON.xContent().createParser(XContentParserConfiguration.EMPTY, testJSON)) {
            controller.process("operator", parser, (e) -> x.set(e));
            assertTrue(x.get() instanceof IllegalStateException);
            assertThat(x.get().getMessage(), containsString("Error processing state change request for operator"));
        }
        testJSON = """
            {
                 "metadata": {
                     "version": "1234",
                     "compatibility": "8.4.0"
                 },
                 "state": {
                     "cluster_settings": {
                         "indices.recovery.max_bytes_per_sec": "50mb",
                         "cluster": {
                             "remote": {
                                 "cluster_one": {
                                     "seeds": [
                                         "127.0.0.1:9300"
                                     ]
                                 }
                             }
                         }