Per T275894, Readers Web intend to increase the scope of the
UniversalLanguageSelector instrument to help them understand how
users are interacting with the Languages list in sidebar.
In order to keep the UniversalLanguageSelector extension focussed and
not overly Wikimedia-specific, it was agreed that the instrument would
be migrated to the WikimediaEvents extension, where other such
instruments are located.
Therefore, remove all code related to the UniversalLanguageSelector
instrument.
Bug: T275894
Depends-On: I2acee8ba8dc59c497dc6ba42cd5bd88dfd985c8b
Change-Id: I72b1d0ff35488521b3499e9606efee26baff8c00
852d72e66d