UserTest: Fix edit count test which incorrectly added user to db

Although 'added' to the database, the user name was cleared
in User::loadDefaults() and not added correctly to the database.

Then if one has BetaFeatures extension, then the test fails.
Via a hook, BetaFeatures does "User::newFromName( $user->getName() );",
that produces a null object as name is '127.0.0.1' and then
$user->getOption() fails.

loadDefaults() is automatically called by addToDatabase() with correct
parameters, so we can just remove the call.

Bug: 68626
Change-Id: Ibb5c60192eb83b2608f72b59d7705854549a5dac
Merge "UserTest: Fix edit count test which incorrectly added user to db"