[llvm] [Analysis][EphemeralValuesAnalysis][NFCI] Remove EphemeralValuesCache class (PR #132454)

[via llvm-commits]

vporpo wrote:

Good catch @nikic , I did notice a small compile-time increase compared to the previous one on the workload that was triggering the quadratic behavior but I assumed it was system noise, but now that I look into it I do see that the InlinerPass is 25% slower than before (but still way faster than without the Ephemeral Values Caching).

I will revert the patch to investigate it further.

https://github.com/llvm/llvm-project/pull/132454