Only the group_salesman can see the opportunities statbuttons
Fix a few not-smart mass_mailing tests:
- running the mass mailing queue processes the messages as the user
running the queue, and will try to send the demo messages, depending
on demo data (when re-running the tests) the test user may not have
the accesses required; sending just the one test email avoids that
issue
- the leads kpi assumes the user has access to leads, that ain't
necessarily the case
For the second issue, when sending statistics if the mailing has a
user `_prepare_statistics_email_values` should be called with that
user as "current" (cf `_action_send_statistics`), so we can just work
off of the current env, though it might be a good idea to eventually
check that.
closesodoo/odoo#89774
X-original-commit: 39af865800c6752b60171f16d6056ceb3c5a1636
Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>