Revert "Add shutdownHook to send sigterm to ryuk (#7717)"

This reverts commit 39f0219.

Author: eddumelendez

core/src/main/java/org/testcontainers/utility/RyukResourceReaper.java

@@ -77,19 +77,6 @@ private synchronized void maybeStart() {
 
         ryukContainer.start();
 
-        Runtime
-            .getRuntime()
-            .addShutdownHook(
-                new Thread(
-                    DockerClientFactory.TESTCONTAINERS_THREAD_GROUP,
-                    () -> {
-                        this.dockerClient.killContainerCmd(this.ryukContainer.getContainerId())
-                            .withSignal("SIGTERM")
-                            .exec();
-                    }
-                )
-            );
-
         CountDownLatch ryukScheduledLatch = new CountDownLatch(1);
 
         String host = ryukContainer.getHost();