Add a new knob to separately enable the autotuning in Triton. (#96440)
Summary: separate triton pointwise autotune from matmul autotune, work done by ckluk
Test Plan: sandcastle + CI
Differential Revision: D43955699
Pull Request resolved: https://github.com/pytorch/pytorch/pull/96440
Approved by: https://github.com/ngimel, https://github.com/jansel
