Modify pipeline library tests to always specify the layout

Modify pipeline library tests to always specify the layout

A recent Vulkan spec change for the VK_KHT_graphics_pipeline_library
extension now requires the VkGraphicsPipelineCreateInfo.layout
field to always be valid for final-link pipelines and never NULL.

Several tests were still using a NULL layout for either the fast
link or optimized link.

This CL updates all tests to now specify a valid layout and
also removes a test variant that explicitly tested the NULL case.

Affects:

dEQP-VK.pipeline.*

Components: Vulkan

VK-GL-CTS Issue: 3661

Change-Id: I5471a9381c3be6e110106004bc3a22110b144864