tu: Do not flush ccu in clear/blits during renderpass
For clear/blits ccu flush not only worse for perf, but also messes up flush_bits when executed in a conditional set of commands.
We already don't flush for 3d blits.
Closes: #6419 (closed)
Fixes: 487aa807 ("tu: Rewrite flushing to use barriers")
Let's see what CI says.