Skip tests with TS command for non-snapshot builds (elastic#131518)

The `TS` source is guarded by a feature flag.

Fixes elastic#131500

Author: kkrik-es

x-pack/plugin/downsample/src/internalClusterTest/java/org/elasticsearch/xpack/downsample/DownsampleIT.java

@@ -7,6 +7,7 @@
 
 package org.elasticsearch.xpack.downsample;
 
+import org.elasticsearch.Build;
 import org.elasticsearch.action.admin.indices.delete.DeleteIndexRequest;
 import org.elasticsearch.action.admin.indices.delete.TransportDeleteIndexAction;
 import org.elasticsearch.action.admin.indices.rollover.RolloverRequest;
@@ -215,6 +216,10 @@ public void testAggMetricInEsqlTSAfterDownsampling() throws Exception {
         };
         bulkIndex(dataStreamName, nextSourceSupplier, 100);
 
+        if (Build.current().isSnapshot() == false) {
+            return;
+        }
+
         // Since the downsampled field (cpu) is downsampled in one index and not in the other, we want to confirm
         // first that the field is unsupported and has 2 original types - double and aggregate_metric_double
         try (var resp = esqlCommand("TS " + dataStreamName + " | KEEP @timestamp, host, cluster, cpu")) {