Group E-mail settings stuff in Setup.php

- Move the overrides of e-mail settings along with other
  configuration corrections instead of being near global object
  definitions
- Also force $wgUseEnotif to false if $wgEnableEmail;
  previously it could remain true since $wgEnotifUserTalk
  and $wgEnotifWatchlist were forced to false after they
  were checked to set $wgUseEnotif
- Also put the removal of 'enotifminoredits' preference nearby

Change-Id: I9af6bb78d34ce053fc36eaa7cc3852de3ecbee8e
Merge "Group E-mail settings stuff in Setup.php"