SwiftShader can allow for a platform-indendent replay. This is useful
for re-tracing. By default disable the SwiftShader test configs unless
we pass in --enable-all-trace-tests.

Also disable the mock ICD trace tests by default.

Bug: angleproject:5134
Change-Id: Ibf1f3ebd6c17f15123705b7d4d9ddd6308f873f3
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2502311
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Cody Northrop <cnorthrop@google.com>
Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>