[NFC][AMDGPU] Update and.ll test and automate check line generation (#145371)

- Convert the test to use update_llc_test_checks.py.
- Use different check prefixes for the different -mcpu options.
- Remove unused xnack 'off' flag.

GitOrigin-RevId: bfde1477617f6c35e5218bb8dbcf7b3905ce0cdd
1 file changed