Fix retrievePluginsInfo API method

[SugaryLump]

The retrievePluginsInfo method was inadvertently removing non-listable plugin info from the plugin manager instead of simply filtering it out from the response as intended. Additionally, some usages of the method (ingest plugin parameter layout building) did not want this plugin info to be filtered out in the first place.

• The method now clones the working list of plugin info to prevent erasing data from the plugin manager's own list
• The method now receives an optional flag indicating whether not-listable plugins will be filtered from the response (default behavior is to filter)