If we bound 4 render targets but we only write to 1 of them, the other 3 need
their contents preserved. This requires either properly configuring HSR to
implement colour masking (TODO) or using the big hammer of setting TRANSLUCENT.
This patch picks the latter for now.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25052>