Support of configuring new values to tweak resources / performance

Is your feature request related to a problem? Please describe.

Regarding https://github.com/zowe/docs-site/pull/4504 there are some values (Tomcat thread pool, direct memory) that cannot be set directly to a service. It is necessary to set via system environment. These are shared between services which does not make sense.

The aim is to support these configuration via script and document it int he article.

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Start with the configuration approach discussed in docs-site/pull/4504 and identify how service settings are currently supplied through the system environment. Focus on the Tomcat thread pool and direct-memory values, then determine the script changes and article updates needed to configure them per service. Done means the values can be configured through the script and the behavior is documented.