zink: disable render_condition_enable during blit

We don't support stencil-exports yet, and even when we will, we might not support it on all hardware. So we really need an alternative plan here, even when render_condition_enable is true.

Fixing this properly is much more involved, and depends on reworking render-condition along the lines that we do in !7746 (closed) to support pausing and resuming properly first. So let's do the minimal thing, which is to allow this to work in cases where no render-condition is active.

Fixes: 767f70df ("gallium/util: fix util_can_blit_via_copy_region for conditional rendering") Closes: #4047 (closed)