Fix sync problems in conditional_rendering.draw_clear tests

Fix sync problems in conditional_rendering.draw_clear tests

* Invalidate results buffer allocations before attempting to read data.

* Fix synchronization of m_conditionalRenderingBuffer instead of
  m_resultBuffer before verifying its contents.

* Check for vertexPipelineStoresAndAtomics when needed.

* Split update_with_rendering tests in two render passes so
  buffer synchronization works properly and passes validation.

Affected tests:
dEQP-VK.conditional_rendering.draw_clear.*

Components: Vulkan
VK-GL-CTS issue: 2703

Change-Id: I2ae26e19e37c323bdbf94cade419fe5be3ed4f5c