Make scheme test actions parallelizable

[pepicrft]

Short description 📝

I'm enabling parallelization in the project schemes. I guess that it'll cause some flakiness because we have a bunch of shared states around that might leak across tests. If that's the case, it validates that we should invest in a solution like context to control the isolation of the subject under tests.

[fortmarek]

We'll need to skip parallelization of test cases that interact with the simulator. Otherwise, as long as the tests pass, this looks good 👍