Fix depth/stencil image logging in renderpass tests

Fix depth/stencil image logging in renderpass tests

Renderpass tests checking results in depth/stencil images containing
both depth and stencil aspects attempt to log the depth/stencil image
when the test fails (but not when the test passes).

When the logging facilities log those depth/stencil images, they convert
them to an image set with two images in order to separate the depth and
stencil views. If this image set is logged as part of another image set
in the log, the logging facilities fail an assertion because image sets
cannot contain other image sets.

Affected tests (only on failures for depth/stencil formats):
dEQP-VK.renderpass*.*allocation.simple.*
dEQP-VK.renderpass*.*allocation.formats.*
dEQP-VK.renderpass*.*allocation.attachment.*
dEQP-VK.renderpass*.*allocation.attachment_allocation.*
dEQP-VK.renderpass*.*allocation.attachment_write_mask.*

Components: Vulkan
VK-GL-CTS issue: 2642

Change-Id: I72ba603e3b42b34730f1f51234f0b6cd64f23da2