[fix][test] Fix flaky test MetadataStoreTest.emptyStoreTest (#23998)

Author: lhotari

pulsar-metadata/src/test/java/org/apache/pulsar/metadata/MetadataStoreTest.java

@@ -114,7 +114,7 @@ public void concurrentPutTest(String provider, Supplier<String> urlSupplier) thr
                 MetadataStoreConfig.builder().fsyncEnable(false).build());
 
         String data = "data";
-        String path = "/non-existing-key";
+        String path = "/concurrentPutTest";
         int concurrent = 50;
         List<CompletableFuture<Stat>> futureList = new ArrayList<>();
         for (int i = 0; i < concurrent; i++) {