Fix file settings service test on windows (#115234) (#115502)

Backports #115234

Author: n1v0lg

muted-tests.yml

@@ -338,9 +338,6 @@ tests:
 - class: org.elasticsearch.xpack.inference.TextEmbeddingCrudIT
   method: testPutE5Small_withPlatformSpecificVariant
   issue: https://github.com/elastic/elasticsearch/issues/113950
-- class: org.elasticsearch.reservedstate.service.FileSettingsServiceTests
-  method: testProcessFileChanges
-  issue: https://github.com/elastic/elasticsearch/issues/115280
 - class: org.elasticsearch.xpack.esql.qa.mixed.MixedClusterEsqlSpecIT
   issue: https://github.com/elastic/elasticsearch/issues/115315
 - class: org.elasticsearch.upgrades.UpgradeClusterClientYamlTestSuiteIT

server/src/test/java/org/elasticsearch/reservedstate/service/FileSettingsServiceTests.java

@@ -250,7 +250,7 @@ public void testProcessFileChanges() throws Exception {
         fileSettingsService.start();
         fileSettingsService.clusterChanged(new ClusterChangedEvent("test", clusterService.state(), ClusterState.EMPTY_STATE));
         // second file change; contents still don't matter
-        writeTestFile(fileSettingsService.watchedFile(), "{}");
+        overwriteTestFile(fileSettingsService.watchedFile(), "{}");
 
         // wait for listener to be called (once for initial processing, once for subsequent update)
         assertTrue(latch.await(20, TimeUnit.SECONDS));
@@ -355,6 +355,12 @@ public void testHandleSnapshotRestoreResetsMetadata() throws Exception {
     private void writeTestFile(Path path, String contents) throws IOException {
         Path tempFilePath = createTempFile();
         Files.writeString(tempFilePath, contents);
-        Files.move(tempFilePath, path, StandardCopyOption.ATOMIC_MOVE);
+        Files.move(tempFilePath, path, StandardCopyOption.ATOMIC_MOVE, StandardCopyOption.REPLACE_EXISTING);
+    }
+
+    private void overwriteTestFile(Path path, String contents) throws IOException {
+        Path tempFilePath = createTempFile();
+        Files.writeString(tempFilePath, contents);
+        Files.move(tempFilePath, path, StandardCopyOption.REPLACE_EXISTING);
     }
 }