Fix post-clear barrier in depth/stencil descriptor tests

Fix post-clear barrier in depth/stencil descriptor tests

After clearing the color and depth/stencil image, the tests were using a
barrier to VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT with an access mask of 0.
This commit fixes that barrier to use VK_PIPELINE_STAGE_ALL_GRAPHICS_BIT
and an access mask covering all uses of these descriptors in the render
pass.

Affected tests:
dEQP-VK.image.depth_stencil_descriptor.*

Components: Vulkan
VK-GL-CTS issue: 3305

Change-Id: I7d8c41b3dbbe69f3a613ba1bd09a0482f77133f2