All start.d ini parameters become viewable; non obvious

**Jetty version(s)**
Jetty 12

**Enhancement Description**
Contents of ini files in start.d turn into process parameters. It's non-obvious that settings, possibly protected by file permissions, become part of the publicly viewable process arguments. This isn't great for anything that contains a password, like start.d/ssl.ini.

It looks like it happens here: https://github.com/jetty/jetty.project/blob/dde6ae18f93a2b82e900ceb8b79210f44948e79d/jetty-home/src/main/resources/bin/jetty.sh#L571

The best solution would be for the file contents to remain hidden. At the least, ssl.ini and similar should locally document that all values become public.