Mailing statistics emails are build on digest layout. This layout contains a
reference to the digest unsubscribe mechanism, which obviously does not work
with mailing statistics emails as they currently have no opt-out mechanism.
This commit fixes that part of the template so that unsubscribe is displayed
only with digests.
Task-2582128 (Digest onboarding and usage improvement)
Task-2686586 (Repair mailing statistics email)
X-original-commit: febe4506cf14ba9308d85538515eb61c4638b18d
Part-of: odoo/odoo#79877
Thibault Delavallée
db5315efad