[SLP]Do not include the cost of and -1, <v> and emit just <v> after MinBitWidth.

After minbitwidth analysis, and <v>, (power_of_2 - 1 const) can be
transformed into just an <v>, (all_ones const), which can be ignored at
the cost estimation and at the codegen. x264 benchmark has this pattern.

Reviewers: RKSimon

Reviewed By: RKSimon

Pull Request: https://github.com/llvm/llvm-project/pull/90739