Fix SecurityNetty4HttpServerTransportTests (#95913)

Fixes SecurityNetty4HttpServerTransportTests
testAuthnContextWrapping

The mocking removed code that called release on request objects.

Closes #95846

x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/transport/netty4/SecurityNetty4HttpServerTransportTests.java

@@ -283,6 +283,7 @@ public class SecurityNetty4HttpServerTransportTests extends AbstractHttpServerTr
         final HttpServerTransport.Dispatcher dispatcher = new HttpServerTransport.Dispatcher() {
             @Override
             public void dispatchRequest(final RestRequest request, final RestChannel channel, final ThreadContext threadContext) {
+                request.getHttpRequest().release();
                 // STEP 2: store the dispatched request, which should be wrapping the context
                 dispatchedHttpRequestReference.set(request.getHttpRequest());
             }