Remove e3.clickTrack() and e3.isUserAnonymous()

e3.clickTrack() was a wrapper for ClickTracking API call,
e3.isUserAnonymous() did the same as mw.user.isAnon().
They have no callers in 1.21wmf9 and above.

Change-Id: I3ab683ef8cda18183a7992711ab836a4bcc77c14