Resolve "Add clean-up of droplets on the cleanup stage"

Closes #201

See merge request openappstack/bootstrap!106

Resolve "Upgrade to debian buster"

Closes #123

See merge request openappstack/bootstrap!101

Resolve "Remove stale CI droplets after a given time"

Closes #28

See merge request openappstack/bootstrap!98

Merge branch '28-remove-stale-ci-droplets-after-a-given-time' of code.greenhost.net:openappstack/bootstrap into 28-remove-stale-ci-droplets-after-a-given-time

Resolve "Nextcloud+collabora installation fails randomly"

Closes #188

See merge request openappstack/bootstrap!97

Resolve "Incompatible helm client and server versions"

Closes #183

See merge request openappstack/bootstrap!95

Resolve "Don't fail CI when LE cert fetching is delayed"

Closes #135

See merge request openappstack/bootstrap!92

Resolve "Add Prometheus and Grafana"

Closes #187 and #140

See merge request openappstack/bootstrap!80

Resolve "Install krew plugin manager for kubectl"

Closes #177

See merge request openappstack/bootstrap!91

Resolve "Personal cluster doesn't use proper LE certs"

Closes #180 and #179

See merge request openappstack/bootstrap!93

Closes #135

Closes #183

Closes #179

Closes #180

add test/rke.log to CI artifacts, also fix problem in gitignore

See merge request openappstack/bootstrap!94

I removed the "stop" option, because that would lead to only 1 failed
test being retried. Any test that would have run after the failed test
will not run the first time (because "stop" was true) *and* not be added
to the rerun (because they didn't fail).