Jetty 12 - Optimize RequestLog information retrieval

[sbordet]

Jetty version(s)
12+

Enhancement Description
Following the comments in #8705, we should find a more efficient way to extract information from the current Jakarta EE request to be stored in the Jetty core request so that it is accessible to the RequestLog.
In particular, information that are specific to Jakarta EE such as the remote user, the real path and the Servlet name.

The RequestLog implementation should collaborate and expose whether it really need those information, so that if it is not needed it is not retrieved nor stored.

The ideas in #8705 are too specific to a particular implementation of RequestLog, the CustomRequestLog, but the mechanism should be generic.

[github-actions]

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