Implement proper fix for flaky capybara tests

[laugmanuel]

We currently use capybara/selenium-webdriver to run integration tests with javascript capability.

For whatever reason, these tests are relatively flaky and sometimes fail without any real error output.
In #63 a retry mechanism was introduced to workaround those errors.

We should find the root cause for these problems and fix them - and then remove the retry mechanism in Github actions.