[sdk-platform-java] gax-java(windows): Flaky BatcherImplTest.testElementsNotLeaking

[Flaked](https://github.com/googleapis/gapic-generator-java/actions/runs/4109606391/jobs/7105503631) on Java 11

```
Error: Tests run: 24, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 25.322 s <<< FAILURE! - in com.google.api.gax.batching.BatcherImplTest
Error: com.google.api.gax.batching.BatcherImplTest.testElementsNotLeaking Time elapsed: 1.47 s <<< ERROR!
org.junit.runners.model.TestTimedOutException: test timed out after 500 milliseconds
at java.base@11.0.18/jdk.internal.misc.Unsafe.park(Native Method)
at java.base@11.0.18/java.util.concurrent.locks.LockSupport.park(LockSupport.java:194)
at java.base@11.0.18/java.util.concurrent.FutureTask.awaitDone(FutureTask.java:447)
at java.base@11.0.18/java.util.concurrent.FutureTask.get(FutureTask.java:190)
at app//com.google.api.gax.batching.BatcherImplTest.testElementsNotLeaking(BatcherImplTest.java:448)
at java.base@11.0.18/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base@11.0.18/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base@11.0.18/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base@11.0.18/java.lang.reflect.Method.invoke(Method.java:566)
at app//org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
at app//org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at app//org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
at app//org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at app//org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:299)
at app//org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:293)
at java.base@11.0.18/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base@11.0.18/java.lang.Thread.run(Thread.java:829)
```
...
```
Error: Errors:
Error: BatcherImplTest.testElementsNotLeaking:448 � TestTimedOut test timed out after 500 milliseconds
```

Start with BatcherImplTest.testElementsNotLeaking at line 448 and run the test on Windows with Java 11, where the timeout was observed. Investigate the timeout and confirm the test completes reliably without the 500-millisecond failure; the issue does not identify a source file or a specific fix.

索引モデルが issue の本文から書いたものです。