iris: Disable aux for sampling/images when disabling it for rendering
When disable_rb_aux_buffer detects that an image is bound for rendering at the same time that it's bound as a sampler or image view, it flags that we should disable aux for the render target. Unfortunately, we mistakenly ignored this when preparing access for the sampler/image view and kept using the original aux usage there, rather than AUX_USAGE_NONE.
Closes: #7272 (closed)