Fix unit tests when $wgEmailAuthentication is set to false

Since d2a5cf3 (I0b906b23de), 'emailaddress' and 'emailauthentication'
fields don't have any more CSS classes when $wgEmailAuthentication is
set to false which is breaking the tests.

Force $wgEmailAuthentication to true, so that the tests work in all cases.

Change-Id: Idc156f88ff1bc8595009056166f13191cf5c5c25
Merge "Fix unit tests when $wgEmailAuthentication is set to false"