[llvm] [CodeGen] Make the parameter TRI required in some functions. (PR #85968)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

It also moves the TRI argument earlier in the findRegister* calls - while the isKill/isDead/Overlap flag args tend to be optional the TRI is less likely so (plus people have been lazy...). Once this cleanup is in place we're hoping to get most calls with nullptr TRI correctly updated, as we add test coverage.

https://github.com/llvm/llvm-project/pull/85968