Allow more time for restart tests to reach yellow state. (#48434) (#48480)

The testWatcher method will on occasion timeout waiting for
a yellow cluster state. This change increases the timeout
to 60s.

Author: jakelandis

x-pack/qa/full-cluster-restart/src/test/java/org/elasticsearch/xpack/restart/FullClusterRestartIT.java

@@ -602,7 +602,7 @@ private void assertBasicWatchInteractions() throws Exception {
     private void waitForYellow(String indexName) throws IOException {
         Request request = new Request("GET", "/_cluster/health/" + indexName);
         request.addParameter("wait_for_status", "yellow");
-        request.addParameter("timeout", "30s");
+        request.addParameter("timeout", "60s");
         request.addParameter("wait_for_no_relocating_shards", "true");
         if (getOldClusterVersion().onOrAfter(Version.V_6_2_0)) {
             request.addParameter("wait_for_no_initializing_shards", "true");