tests: Make ExecuteCommandsPrimaryCB more focused
tests: Make ExecuteCommandsPrimaryCB more focused

This test had some complications:
- It tried to record an invocation of a command buffer into itself.
- The renderpass instance was configured for inline commands rather than
  CmdExecuteCommands.

Split out the victim CB, and start the renderpass instance correctly.

There's still a complaint during cleanup that the inner command
buffer is still in use -- but fixing that last problem requires more
substantial changes.

Signed-off-by: Chris Forbes <c3279c50043e18e9442c1ae071cafa0e7a4ca967@google.com>

KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers