Update Netty and OkHttp dependencies and resolve test failures (#3066)

This commit updates several dependencies in dependencies.gradle and resolves the resulting test failures:
- Netty: Updated strict upper bound from <4.2.0 to <5.0.0 (resolved to 4.2.14.Final).
- OkHttp: Removed strict upper bound of <5.0.0 and moved to dynamic versions section (resolved to 5.3.2).
- Cleaned up dependencies.gradle by moving strict dependencies (secretmanager, common-protos, gax) out of the dynamic versions section.
- Updated all gradle.lockfile files.

Resulting test fixes:
- Netty: Replaced NioEventLoopGroup with DefaultEventLoopGroup in NettyExtension and ProbingStepTest. In Netty 4.2+, LocalServerChannel no longer supports registration with NIO-backed event loops, throwing an IllegalArgumentException.
- OkHttp: Refactored ServiceMonitoringClient to safely handle empty responses using Optional.orElse(). In OkHttp 5.x, a 204 No Content response returns a non-null ResponseBody with an empty string, causing an assertion failure where MosApiException was incorrectly bypassed.

networking/src/test/java/google/registry/networking/handler/NettyExtension.java

@@ -32,11 +32,11 @@ import io.netty.channel.ChannelHandler;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;
 import io.netty.channel.ChannelInitializer;
+import io.netty.channel.DefaultEventLoopGroup;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.local.LocalAddress;
 import io.netty.channel.local.LocalChannel;
 import io.netty.channel.local.LocalServerChannel;
-import io.netty.channel.nio.NioEventLoopGroup;
 import io.netty.util.ReferenceCountUtil;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
@@ -54,7 +54,7 @@ public final class NettyExtension implements AfterEachCallback {
   // All I/O operations are done inside the single thread within this event loop group, which is
   // different from the main test thread. Therefore synchronizations are required to make sure that
   // certain I/O activities are finished when assertions are performed.
-  private final EventLoopGroup eventLoopGroup = new NioEventLoopGroup(1);
+  private final EventLoopGroup eventLoopGroup = new DefaultEventLoopGroup(1);
 
   // Handler attached to server's channel to record the request received.
   private EchoHandler echoHandler;