Fix flaky FileIOTest.testMatchWatchForNewFiles test under CI filesystems

addresses #19480

The `FileIOTest.testMatchWatchForNewFiles` test occasionally flakes in the CI environment because the `updOptions` configuration in `CopyFilesFn` does not preserve file attributes when overwriting existing files. In some CI filesystems, this causes the copied file to register a `lastModifiedMillis` timestamp of `0`. Thus, when `ExtractFilenameAndLastUpdateFn` parses this file, it throws a `RuntimeException` at `FileIO.java:800`, failing the pipeline run.

This PR adds `StandardCopyOption.COPY_ATTRIBUTES` to preserve the file's original timestamps, avoiding the exception.

Author: bvolpato

sdks/java/core/src/test/java/org/apache/beam/sdk/io/FileIOTest.java

@@ -249,16 +249,18 @@ public void processElement(ProcessContext context, @StateId("count") ValueState<
       context.output(Objects.requireNonNull(context.element()).getValue());
 
       CopyOption[] cpOptions = {StandardCopyOption.COPY_ATTRIBUTES};
-      CopyOption[] updOptions = {StandardCopyOption.REPLACE_EXISTING};
+      CopyOption[] updOptions = {
+        StandardCopyOption.REPLACE_EXISTING, StandardCopyOption.COPY_ATTRIBUTES
+      };
       final Path sourcePath = Paths.get(sourcePathStr);
       final Path watchPath = Paths.get(watchPathStr);
 
       if (0 == current) {
-        Thread.sleep(100);
+        Thread.sleep(500);
         Files.copy(sourcePath.resolve("first"), watchPath.resolve("first"), updOptions);
         Files.copy(sourcePath.resolve("second"), watchPath.resolve("second"), cpOptions);
       } else if (1 == current) {
-        Thread.sleep(100);
+        Thread.sleep(500);
         Files.copy(sourcePath.resolve("first"), watchPath.resolve("first"), updOptions);
         Files.copy(sourcePath.resolve("second"), watchPath.resolve("second"), updOptions);
         Files.copy(sourcePath.resolve("third"), watchPath.resolve("third"), cpOptions);