Adds a workaround to use draw calls to clear color instead of
vkCmdClearAttachment when the clear happens in the middle of render
pass.  On Pixel phones, vkCmdClearAttachment races with the previous
draw calls in the render pass.

Bug: b/166809097
Change-Id: I8c96b87793da191757635658ad4ee2c3a7875aca
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2382416
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
Reviewed-by: Tim Van Patten <timvp@google.com>