Use IllegalArgumentException when state is used in mixed cluster

Author: JeremyDahlgren

server/src/main/java/org/elasticsearch/rest/action/admin/cluster/RestGetSnapshotsAction.java

@@ -137,7 +137,7 @@ public RestChannelConsumer prepareRequest(final RestRequest request, final NodeC
  } else if (clusterSupportsFeature.test(GetSnapshotsFeatures.GET_SNAPSHOTS_STATE_PARAMETER)) {
  getSnapshotsRequest.states(EnumSet.copyOf(Arrays.stream(stateString.split(",")).map(SnapshotState::valueOf).toList()));
  } else {
- throw new IllegalStateException("[state] parameter is not supported on all nodes in the cluster");
+ throw new IllegalArgumentException("[state] parameter is not supported on all nodes in the cluster");
  }
 
  // Consume these response parameters used in SnapshotInfo now, to avoid assertion errors in BaseRestHandler for requests where they