karma is looking for the chromium exedcutable, but the playwright one is still
called "chrome". I didn't noticed this because it would fall back to the debian install
chromium instance then.

And adjust for the import changes

Newest Ubuntu switched Firefox to a snap, which breaks karma.

Try to use playwright to download and cache firefox/chromium
and use those for karma.

Compared to puppeteer where we did this some time ago this caches
the browsers globally, and only downloads them when we start the tests.

The CI server can be slow from time to time, give it more time

While it's nice to have a fixed chrome version it slows down the yarn install,
downloads a lot of things, and the chrome version depends on various
system packages so one needss to have chromium installed anyway.

This means developers that want to work on tests need firefox and chdomium installed.

Sadly I couldn't find a way to make browsers optional in case the developer
only has one installed.