Test conditional rendering does not affect render pass clears

Test conditional rendering does not affect render pass clears

Clearing attachments at the start of the render pass should happen
unconditionally even if the render pass falls inside a conditional
rendering block.

Affected and new tests:
dEQP-VK.conditional_rendering.*

Components: Vulkan
VK-GL-CTS issue: 3710

Change-Id: I826a787b5cf3b61f2a08c9ce381d29e931653be6