Remove 2+1 more locked/unused extensions from Wikimedia

ClientSide is used only on usabilitywiki, locked.
ActiveStrategy is used only on strategywiki, locked.
Dontswitchmeover unused.

Change-Id: I628faf94331f7f0a1d6234690ef37e2dc2fdc8bc
Merge "Remove 2+1 more locked/unused extensions from Wikimedia"