[test] fix `usbdev_deep_disconnect_test` flakiness on cw310

[timothytrippel]

@timothytrippel The failed test: usbdev_deep_disconnect_test in the CI should be unrelated to this PR since this PR only adds new e2e tests and doesn't modify the existing usb driver code or that failed usb test. I can observe that usbdev_deep_disconnect_test also failed in the CI from a different PR: https://github.com/lowRISC/opentitan/actions/runs/20354991553/job/58596885696?pr=28976#step:6:35068

This test is known to be broken/super flaky on the CW310. Unfortunately, the proper fix for that would be make it work on the CW340 because the CW310 does not support proper USB VBUS management which requires us to do some hacks. I have some WIP code for the CW340 but it is less of a priority (it works on real silicon which is where the most important).

Originally posted by @pamaury in #28789 (comment)