tests: Remove local override for editPage()
tests: Remove local override for editPage()

As far as I can see, it doesn't do anything different from the
parent class.

Bug: T225327
Change-Id: Id52ebd2faa179de39111221e55435e2e6e13aa05

wikimedia/mediawiki-extensions-Echo,wikimedia/mediawiki-extensions-Echo,wikimedia/mediawiki-extensions-Echo,wikimedia/mediawiki-extensions-Echo