Unfortunately this was broken by 605af42e ("Vulkan: Move ICD overrides
to a common place").

This adds an unconditional dependency on the layers to tests. Tests
don't respect angle_enable_vulkan_validation_layers, so we need to ship
the layers irrespective of that setting.

Bug: angleproject:4634
Change-Id: Ided291ea645a72e6c3bdb960e55d15013aa20a3a
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2197279Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>