Considering that 8.0 will EOL in April 2026, and that 8.4 is the current GA version, I don’t think 8.4 is in a position to “mature a bit more.” 
You are correct in that 8.0 audit plugin is removed, and 8.4 audit component should be used instead.
You are also correct that the linked documentation page does not explain how to remove plugins. Use SHOW PLUGINS;, then UNINSTALL PLUGIN XXXX; Then install the component, and configure.