[llvm] [SystemZ] Eliminate call sequence instructions early. (PR #77812)

[Matt Arsenault via llvm-commits]

arsenm wrote:

This seems like an extreme measure to fix the reported issue. We're just missing a helper function to preserve the frame size attributes during a block size split? Seems easier to keep the call frame handling in line with other targets instead of doing something different 

https://github.com/llvm/llvm-project/pull/77812