[InstSimplify] Transform X * Y % Y --> 0

simplifyDiv already handles the case X * Y / Y --> X (barring overflow).
This adds the equivalent handling to simplifyRem.

Correctness:
https://alive2.llvm.org/ce/z/J2cUbS
https://alive2.llvm.org/ce/z/us9NUM
https://alive2.llvm.org/ce/z/AvaDGJ
https://alive2.llvm.org/ce/z/kq9ige

Extending the situations in which we apply this transform would not be
correct:
https://alive2.llvm.org/ce/z/Lf9V63
https://alive2.llvm.org/ce/z/6RPQK3
https://alive2.llvm.org/ce/z/p9UdxC
https://alive2.llvm.org/ce/z/A2zlhE
https://alive2.llvm.org/ce/z/vHTtLw
https://alive2.llvm.org/ce/z/lvpH42

Differential Revision: https://reviews.llvm.org/D102864