[FIX] web: make test more robust

Before this commit, the changed test sometimes failed on runbot
(rarely though), because it might happen that the debounce released
before the promise returned by the click helper resolved (e.g. if
the server was overloaded, or was garbage collecting...). That
promise waited for a setTimeout, and then for a nextAnimationFrame.
In this scenario, there's no need to wait so long, as there is no
rendering to wait for.

Example of failing build: https://runbot.odoo.com/runbot/build/10360554

Part-of: odoo/odoo#78621