Purpose of this commit is to have as less custom test data as possible. In
some sms tests we can re-use existing mailing, leading to more standard
tests and expected results.
We also improve ``gateway_sms_sent_click`` tool that now creates random IP
addresses allowing to have various clicks on a given tracker. Indeed as IP
is unique several clicks are currently set into the same click record, which
will now not be the case anymore.
Task-2641394 (Digest emails sending improvement)
Task-2582128 (Digest onbarding and usage improvement)
Task-2686586 (Repair mailing statistics email)
X-original-commit: f76b154412a111067203979075fa65f198cc39f4
Part-of: odoo/odoo#79877