[llvm] Reland "[llvm][AArch64] Copy all operands when expanding BLR_BTI bundle (#78267)" (PR #78719)

[David Spickett via llvm-commits]

DavidSpickett wrote:

I think I'd prefer to land this first regardless of whether I do Eli's suggestion, to have a solid foundation to work from.

On Monday I will looking into changing `BLR_BTI`, so we can know the trade-offs before Tuesday's deadline.

https://github.com/llvm/llvm-project/pull/78719