[llvm] [AMDGPU] Move AMDGPUCodeGenPassBuilder into AMDGPUTargetMachine(NFC) (PR #103720)

[Christudasan Devadasan via llvm-commits]

cdevadas wrote:

### Merge activity

* **Aug 19, 10:55 AM EDT**: @cdevadas started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/103720).


https://github.com/llvm/llvm-project/pull/103720