Consider replacing Chrome with Chromium in Jenkins docker build image

To prepare for FOLIO-1940 (a general refresh of the Jenkins docker build image jenkins-slave-all), it would be useful to rebuild and deploy the current image. This is a few months old.

(We use Chrome for the headless browser tests via Karma.)

However test builds of jenkins-slave-all show a problem with the current version of Chrome (v75) being included here.

Only the current version of "google-chrome-stable" is available, so we cannot pin to a previous version.

Instead using "chromium-browser" (current release v74) is successful. If ever needed, we would be able to pin to a previous version.