Some strings were not translated in website_forum because translation marks
inside backticks will not be extracted to be translated.
i.e., Markup`${_t("Please translate me"}, OK` will not work.
This commit fixes the issue by explicit translation before putting it inside the
backticks.
Task-3462273
closes odoo/odoo#137857
X-original-commit: 5f33cdb8120661dad58eae9be1d6a511dc712bbd
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>