Correctly use the email_from tag from template.
This partially reverts commit 0f82346167.
"[FIX] email_template: keep email_from and outgoing server"
Remove the email_from part that was incorrect, keeping the one on mail_server_id
Instead of assigning an non-evaulated email_from in the context, specify the
email_from in the onchange method. This way the created email has an evaulated
from value. This was an issue for templates using email_from like
"${(object.user_id.email or '')|safe}"
In the _notify method method, the email_from is partially respected as it will
be used a fallback only. However changing that would introduce a modification of
behaviour not suitable for 7.0 branch.
Fixes#8409
Martin Trigaux
909e6e300a