Remove user messages check during startup

19703ab10826fdcd47c683d27ffe1ca1b2af0ac8 added a check to prevent
user login during initalisation in order to log whether the user
has unread messages on their talk page.

The check used Site.logged_in, however that method will always be
false at initialisation as _userinfo has not been fetched.
(site.py:682 of https://mediawiki.org/wiki/Special:Code/pywikipedia/10285)

Moving the user talk check to 'after' Site.login would complicate
the login sequence, and has little benefit.  A more comprehensive
implementation is needed.  So remove it for now, as it hasnt worked
for a while.

Bug: 69895
Change-Id: Id2c2321a8ebdd4edccb6c6f1731d7461dfd4fbd9
Merge "Remove user messages check during startup"