[llvm] [RISCV] Enable TTI::shouldDropLSRSolutionIfLessProfitable by default (PR #89927)

[Philip Reames via llvm-commits]

preames wrote:

> We've been using -lsr-drop-solution for some benchmarks in our downstream for a while. Overall, I think it has been a net improvement.

This is good to hear.  I have no downstream experience with this change, but also have no objection to landing this.

Given that, LGTM.  We can iterate to improve the couple of regressions in tree.

https://github.com/llvm/llvm-project/pull/89927