Obsolete legacy plugin config override

[herrvigg]

A non-documented feature comes from qTranslate-X to handle specific configuration files for the old legacy integration plugins such as woocommerce-qtranslate-x.

On activation/deactivation of the plugins, the principle is that qTranslate updates the list of configuration files according to the Integration Guide (some parts still to be verified). A quite complicated sequence ensures that any plugin which directory is ending with -qtranslate-x would override the configuration of related standard candidates plugins.

Since the new modules replace all the legacy plugins, this part becomes obsolete. The activation sequence should be simplified.