Disable Memory Hole for outgoing emails in Tails
As decided on #13649 (closed), we should disable memory hole for outgoing emails
in Tails by default.
This is currently a non issue, because we use torbirdy/stable.
But we should be proactive and explicitly disable the pref now, so we don’t forget about it whenever we upgrade to Torbirdy 0.2.3 or newer for a totally unrelated reason (such as… switching to Debian testing :)
Feature Branch: feature/15201-disable-enigmail-memory-hole