Revert "ensured that deactivated non-XL namespace remains accessible"

this extension does *way* more than just replacing `Iqvoc::Label` -
selectively (de)activating it turns out to be impractical

This reverts commits 99968f99c5daf01694a2a04976bd069533adf974 and
11e03916afd7b67b34602ef3423263546e700b8d.