Remove AutoPlugin triggers from plugins.

With the current triggers, all plugins are enabled by enabling any other
(since all end up triggering on UniversalPlugin). After removing the
triggers, we can still include all plugins via JavaAppPackaging.
This should probably just be part of the RPM plugin (similarly for Debian/Universal/Windows etc.).   The reason we didn't do this initially was because these settings were more experimental.  Having used them in several projects, we can just embed them in the raw plugins now, in my opinion.