Handle createLink post security manager in StoreRecoveryTests (elastic#129964)

When running under security manager an assumptionw as made that failing
to create a hard link due to security exception implied hard links were
supported. Now that security manager is gone, the code to create a hard
link in StoreRecoveryTests executes. But in the case of windows,
BasicFileAttributes.fileKey does not return a unique object that can be
used to verify a link exists. Yet the fact createLink returned is enough
to trust the jdk was able to create a link.

closes elastic#124104

Author: rjernst

muted-tests.yml

@@ -236,9 +236,6 @@ tests:
 - class: org.elasticsearch.packaging.test.DockerTests
   method: test012SecurityCanBeDisabled
   issue: https://github.com/elastic/elasticsearch/issues/116636
-- class: org.elasticsearch.index.shard.StoreRecoveryTests
-  method: testAddIndices
-  issue: https://github.com/elastic/elasticsearch/issues/124104
 - class: org.elasticsearch.smoketest.MlWithSecurityIT
   method: test {yaml=ml/data_frame_analytics_crud/Test get stats on newly created config}
   issue: https://github.com/elastic/elasticsearch/issues/121726

server/src/test/java/org/elasticsearch/index/shard/StoreRecoveryTests.java

@@ -44,7 +44,6 @@
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.nio.file.attribute.BasicFileAttributes;
 import java.util.Arrays;
 import java.util.Map;
 import java.util.function.Predicate;
@@ -254,12 +253,7 @@ public boolean hardLinksSupported(Path path) throws IOException {
         try {
             Files.createFile(path.resolve("foo.bar"));
             Files.createLink(path.resolve("test"), path.resolve("foo.bar"));
-            BasicFileAttributes destAttr = Files.readAttributes(path.resolve("test"), BasicFileAttributes.class);
-            BasicFileAttributes sourceAttr = Files.readAttributes(path.resolve("foo.bar"), BasicFileAttributes.class);
-            // we won't get here - no permission ;)
-            return destAttr.fileKey() != null && destAttr.fileKey().equals(sourceAttr.fileKey());
-        } catch (SecurityException ex) {
-            return true; // if we run into that situation we know it's supported.
+            return true; // createLink returning without exception means hard links are supported
         } catch (UnsupportedOperationException ex) {
             return false;
         }