Randomly failing metrics test

This test seems to still fail randomly/rarely during CI builds unfortunately I cannot reproduce this error locally.

````txt
MetricCollectingInterceptorTest > testMetricsFailedCall() FAILED
org.opentest4j.AssertionFailedError: execution timed out after 1000 ms
at org.junit.jupiter.api.AssertTimeout.assertTimeoutPreemptively(AssertTimeout.java:158)
at org.junit.jupiter.api.AssertTimeout.assertTimeoutPreemptively(AssertTimeout.java:119)
at org.junit.jupiter.api.AssertTimeout.assertTimeoutPreemptively(AssertTimeout.java:101)
at org.junit.jupiter.api.AssertTimeout.assertTimeoutPreemptively(AssertTimeout.java:97)
at org.junit.jupiter.api.Assertions.assertTimeoutPreemptively(Assertions.java:3323)
at net.devh.boot.grpc.test.metric.MetricCollectingInterceptorTest.testMetricsFailedCall(MetricCollectingInterceptorTest.java:497)

Caused by:
org.junit.jupiter.api.AssertTimeout$ExecutionTimeoutException: Execution timed out in thread junit-timeout-thread-6
at sun.misc.Unsafe.park(Native Method)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(AbstractQueuedSynchronizer.java:997)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1304)
at java.util.concurrent.CountDownLatch.await(CountDownLatch.java:231)
at net.devh.boot.grpc.test.metric.MetricCollectingInterceptorTest$$Lambda$1056/1236908650.execute(Unknown Source)
at org.junit.jupiter.api.AssertTimeout.lambda$assertTimeoutPreemptively$2(AssertTimeout.java:102)
at org.junit.jupiter.api.AssertTimeout$$Lambda$1040/1085016662.get(Unknown Source)
at org.junit.jupiter.api.AssertTimeout.lambda$assertTimeoutPreemptively$4(AssertTimeout.java:138)
at org.junit.jupiter.api.AssertTimeout$$Lambda$1041/196414950.call(Unknown Source)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
````

Start with MetricCollectingInterceptorTest.java, especially testMetricsFailedCall() around line 497, and review the CI timeout trace showing CountDownLatch.await. Reproduce the intermittent failure in CI or repeated test runs, then confirm the test completes reliably without the 1000 ms timeout.

Written by the indexing model from the issue text.