Revert "[gicombiner] Add GIMatchTree and use it for the code generation"

All the windows bots are failing match-tree.td and there's no obvious cause that
I can see. It's not just the %p formatting problem. My best guess is that
there's an ordering issue too but I'll need further information to figure that
out. Revert while I'm investigating.

This reverts commit 64f1bb5c and 77d4b5f5