[inductor] Rewrite Triton templates + epilogue fusion (retry) (#91575)
This reverts commit 94262efc7d381ace82aa74ed2f5f5ec76f8fca95 to reland #91105 / #90738.
Fixes https://github.com/pytorch/torchdynamo/issues/2015
Pull Request resolved: https://github.com/pytorch/pytorch/pull/91575
Approved by: https://github.com/ngimel
