[SWDEV-539215] - Autotune support for persistent reduction and no_x_dim removal #2417
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We noticed persistent reduction kernels can be extremely poor performing https://ontrack-internal.amd.com/browse/SWDEV-539215
The root cause is that in certain size restrictions and kernels "no_x_dim" mode is enabled, which embeds static XBLOCK=1 into the kernel. This means tuning is not optimal. Removing this mode and enabling autotune we achieve 2x performance proving that new heuristics must be made.
We will bring this into 2.7 for perf uplift, discussion is undergoing with upstream on removing no_x_dim, if there is no perf regression they are in agreement. Draft PR shows no perf loss on ROCm for any inductor benchmark pytorch#159048
Removing tests because no longer relevant.
Cherry-picked to release/2.8 branch via #2454