Fix number of pipelines/framebuffers/renderpasses created in dynamic offset tests

Fix number of pipelines/framebuffers/renderpasses created in dynamic offset tests

Tests need a pipeline/framebuffer/renderpass per command buffer to be
executed. For the single command buffer case, we were creating an extra
one that is unused.

However, it will produce crashes if we ever add tests with more than
two command buffers, as it is using the command buffer index to get
the respective pipeline/framebuffer/renderpass element to bind.

Components: Vulkan
VK-GL-CTS issue: 2293

Affected tests:

  dEQP-VK.pipeline.dynamic_offset.*

Signed-off-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>
Change-Id: Ie1b2fb80f4fdff56c9e7879c9b1382f61c4ee622