Update Jenkins pipeline

[VincentVerelst]

The unit- and integrationtests have been split in the repo, but not on Jenkins. Currently both are run after each push to each feature branch. Tests take about 35 min to run. We want to change this to:

• run unit tests after each push on each feature branch
• run integrationtests before each push/PR to main branch

[HansVRP]

currently the unit tests are also integrated by github actions.

TODO: refine the jenkins pipeline for integration tests on PR to main