Removes the remaining references to the old port-based exception APIs in
favor of the new channel-based APIs.
Bug: fuchsia:ZX-4031
Test: runtests on emulator and device
Change-Id: Ieac5b66c2f676966d1018d771cab6c8635f12a8f
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/1700321
Reviewed-by: Francois Rousseau <frousseau@google.com>
Commit-Queue: Francois Rousseau <frousseau@google.com>