Vulkan: remove clear depth ability from clearWithDraw This partially reverts the following change: 60ec8f576 Vulkan: break dependency to the depthClamp feature The feature is no longer necessary, and simplifies the usage of utility shaders. Bug: angleproject:2361 Change-Id: I1e87ac8d2517c5a3b50e3d0cddd55c852e0e3e7d Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1555313 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Tobin Ehlis <tobine@google.com>