gitlabci provisions a different OS than locally

[schtibe]

Our gitlabci.sh script contains this line
export VIRTUALIZATION_PARAMETERS_FILE=virtualization/parameters_test.yml

which is a bit problematic because the parameters_test.yml may contain a different configuration than parameters.yml. Just had major issues because the latter contained the directive to use Ubuntu instead of Debian, whereas the _test version didn't

This file is apparently only part of the liip-amboss fork.
My proposal:

• Check if we still need it, or if the main project offers another way of running stuff on CI
• If we do need it, fix it so it'll consider values set in parameters.yml on CI as well