[llvm] [AMDGPU] Run LowerLDS at the end of the fullLTO pipeline (PR #75333)

[Pierre van Houtryve via llvm-commits]

Pierre-vh wrote:

> How difficult would it be to support absolute addresses in the pass?

I'm not sure, that's a question for @JonChesterfield I believe :)
In this case I'm just interested in making the pass able to run more than once to enable some experiments with ``--lto-partitions`

https://github.com/llvm/llvm-project/pull/75333