fix tests

Author: dnhatn

server/src/internalClusterTest/java/org/elasticsearch/search/fieldcaps/FieldCapabilitiesIT.java

@@ -906,6 +906,10 @@ static void unblockOnRewrite() {
 
         @Override
         protected QueryBuilder doRewrite(QueryRewriteContext queryRewriteContext) throws IOException {
+            // skip rewriting on the coordinator
+            if (queryRewriteContext.convertToCoordinatorRewriteContext() != null) {
+                return this;
+            }
             try {
                 blockingLatch.await();
             } catch (InterruptedException e) {