Enhancement: start jetty with http2

Currently the jetty server uses http1.1

```
final ServerConnector sslConnector = new ServerConnector(server,
new SslConnectionFactory(sslContextFactory, "http/1.1"),
new HttpConnectionFactory(httpsConfig));
sslConnector.setPort(httpsPort);
sslConnector.setHost(bindInterface);
server.addConnector(sslConnector);
```

https://github.com/apache/cloudstack/blob/2e9b3d8e084b5f6ddf4690afe266e0a2b3f751bb/client/src/main/java/org/apache/cloudstack/ServerDaemon.java#L240

It would be nice to support http2
https://eclipse.dev/jetty/javadoc/jetty-9/org/eclipse/jetty/http2/server/HTTP2ServerConnectionFactory.html

##### ISSUE TYPE

* Enhancement Request

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##### CLOUDSTACK VERSION

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##### CONFIGURATION

##### OS / ENVIRONMENT

##### SUMMARY

##### STEPS TO REPRODUCE

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##### EXPECTED RESULTS

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##### ACTUAL RESULTS

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从 client/src/main/java/org/apache/cloudstack/ServerDaemon.java 约第 240 行开始，检查现有的 HTTPS ServerConnector 配置。阅读 Jetty 的 HTTP2ServerConnectionFactory 文档，以了解集成点。完成的标准是 CloudStack 的 Jetty 服务器在保持当前 HTTP/1.1 行为的基础上支持 HTTP/2，并建立预期的配置和验证。

由索引模型根据 Issue 内容生成。