Netty: Review `assert` statments

[pnicolucci]

The io.openliberty.mcp.internal_fat fails with the following when jvm.options has -ea

The following exception occurs:

[9/14/25, 22:07:47:011 PDT] 0000003b io.netty.channel.ChannelInitializer                          W Failed to initialize a channel. Closing: [id: 0x8bda7d2d, L:/127.0.0.1:8011 - R:/127.0.0.1:35439]
java.lang.AssertionError
	at io.netty.handler.codec.http2.DefaultHttp2LocalFlowController.windowUpdateRatio(DefaultHttp2LocalFlowController.java:246)
	at com.ibm.ws.http.netty.pipeline.http2.LibertyUpgradeCodec.buildHttp2ConnectionHandler(LibertyUpgradeCodec.java:171)
	at com.ibm.ws.http.netty.pipeline.http2.LibertyUpgradeCodec.createCleartextUpgradeHandler(LibertyUpgradeCodec.java:70)
	at com.ibm.ws.http.netty.pipeline.HttpPipelineInitializer.addH2CCodecHandlers(HttpPipelineInitializer.java:245)
	at com.ibm.ws.http.netty.pipeline.HttpPipelineInitializer.setupH2cPipeline(HttpPipelineInitializer.java:217)
	at com.ibm.ws.http.netty.pipeline.HttpPipelineInitializer.setupUnsecurePipeline(HttpPipelineInitializer.java:153)
	at com.ibm.ws.http.netty.pipeline.HttpPipelineInitializer.initChannel(HttpPipelineInitializer.java:133)
	at io.netty.channel.ChannelInitializer.initChannel(ChannelInitializer.java:129)
	at io.netty.channel.ChannelInitializer.handlerAdded(ChannelInitializer.java:112)
	at io.netty.channel.AbstractChannelHandlerContext.callHandlerAdded(AbstractChannelHandlerContext.java:1130)
	at io.netty.channel.DefaultChannelPipeline.callHandlerAdded0(DefaultChannelPipeline.java:558)
	at io.netty.channel.DefaultChannelPipeline.access$100(DefaultChannelPipeline.java:45)
	at io.netty.channel.DefaultChannelPipeline$PendingHandlerAddedTask.execute(DefaultChannelPipeline.java:1410)
	at io.netty.channel.DefaultChannelPipeline.callHandlerAddedForAllHandlers(DefaultChannelPipeline.java:1064)
	at io.netty.channel.DefaultChannelPipeline.invokeHandlerAddedIfNeeded(DefaultChannelPipeline.java:599)
	at io.netty.channel.AbstractChannel$AbstractUnsafe.register0(AbstractChannel.java:513)
	at io.netty.channel.AbstractChannel$AbstractUnsafe.access$200(AbstractChannel.java:428)
	at io.netty.channel.AbstractChannel$AbstractUnsafe$1.run(AbstractChannel.java:485)
	at io.netty.util.concurrent.AbstractEventExecutor.runTask(AbstractEventExecutor.java:173)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:166)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:569)
	at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:998)
	at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.base/java.lang.Thread.run(Thread.java:853)

See #32870 for additional details

[pnicolucci]

2 PD sizing