[Test] More reliable wait for index to appear

Relates: #125652
Resolves: #126204

Author: ywangd

muted-tests.yml

@@ -360,9 +360,6 @@ tests:
 - class: org.elasticsearch.xpack.esql.qa.single_node.GenerativeIT
   method: test
   issue: https://github.com/elastic/elasticsearch/issues/126139
-- class: org.elasticsearch.snapshots.SharedClusterSnapshotRestoreIT
-  method: testDeletionOfFailingToRecoverIndexShouldStopRestore
-  issue: https://github.com/elastic/elasticsearch/issues/126204
 - class: org.elasticsearch.xpack.esql.inference.RerankOperatorTests
   method: testSimpleCircuitBreaking
   issue: https://github.com/elastic/elasticsearch/issues/124337

server/src/internalClusterTest/java/org/elasticsearch/snapshots/SharedClusterSnapshotRestoreIT.java

@@ -748,7 +748,7 @@ public void testDeletionOfFailingToRecoverIndexShouldStopRestore() throws Except
 
         logger.info("--> wait for the index to appear");
         // that would mean that recovery process started and failing
-        waitForIndex("test-idx", TimeValue.timeValueSeconds(10));
+        safeGet(clusterAdmin().prepareHealth(TEST_REQUEST_TIMEOUT, "test-idx").execute());
 
         logger.info("--> delete index");
         cluster().wipeIndices("test-idx");