Disable unsafe MS Exchange autoconfig method in Thunderbird
While working on #17277 (closed) I noticed that not only had we forgotten to disable the MX autoconfig method, but also the MS Exchange one. However, there seems to be proglems with the latter one, so let’s deal with it in this ticket instead.
Details for the problem can be found here: #17277 (comment 3967)
Feature Branch: bugfix/17654-disable-exchange-autoconfig
Blocked by #17277 (closed)