[llvm] [ValueTracking] Improve `Bitcast` handling to match SDAG (PR #125935)

[Abhishek Kaushik via llvm-commits]

abhishek-kaushik22 wrote:

I was only able to find one more test in the rest of the failures.
Should I commit the tests first to show what's changed more clearly (I had chatgpt name the tests 😄)? @RKSimon 

https://github.com/llvm/llvm-project/pull/125935