[llvm] [RISCV][GISel] Use boolean predicated legalization action methods to remove a custom lambda. (PR #115628)

[Sam Elliott via llvm-commits]

lenary wrote:

Following up, do we think we need several versions of `llvm/test/CodeGen/RISCV/GlobalISel/legalizer-info-validation.mir` which take the predicates into account - presumably coverage is now different depending on the subtarget used. I don't know how much this coverage would help or not, it's unclear if that testcase is for RISC-V, or for GlobalISel - if there's a regression, which is more likely to be the problem?

https://github.com/llvm/llvm-project/pull/115628