Make sure we get all the benefits from TorBirdy's own account wizard

Originally created by @anonym on #11204 (Redmine)

Once we enable the automatic configuration wizard, we will lose out from some of the features of TorBirdy’s wizard:

• Disables check_new_mail so mail is not fetched at some regular interval (every 10 minutes by default).

• Make sure that drafts are saved to Local Folders if it is an IMAP account. This is extremely important! When Enigmail is used, drafts will be encrypted with user’s own key, but only from the point where the user makes it clear that the email should be encrypted. If the user decides this late, the plaintext would leak through any drafts.

• Do not check for new messages at startup.

• Do not automatically download new messages for POP, which I’m not entirely sure what it does (see download_on_biff here.

While I believe some of these can be fixed with prefs, some (e.g. the drafts thing) might require some fixes in TorBirdy,

Feature Branch: feature/6154-secure-autoconfig-in-icedove

Parent Task: #6154 (closed)