Fix marimo e2e tests on mac

[zilto]

Failing tests can be seen here. This is because tests/e2e/helpers/dashboard/test_e2e.py hard codes the dashboard port to 2718. Marimo dynamically allocates the port on which the notebook is served based on the available ports.

Having the end-to-end playwright tests inside common tests makes it inconvenient to disable and skip the check. As mentioned here #2701 (comment), it should have its own CI workflow

[sh-rp]

To me the problem seems to be that the dashboard does not get started on mac (it did before and I can't get it to run). On linux you can see the marimo output in the test logs, on mac they are missing.