[llvm] RFC: [AMDGPU] Stop using attribute groups in CodeGen tests (PR #86157)

[Jay Foad via llvm-commits]

jayfoad wrote:

The patch was generated automatically using this script:
```shell
#!/bin/sh
# Remove attribute groups from file $1.
sed -Ei "$(sed -En 's|^ *attributes (#[0-9]+) = \{ *(( *[^ }])*) *\}|s/\1\\>/\2/|p' "$1" && perl -i -0pe 's/\n+ *attributes #[0-9].*$//gm' "$1")" "$1"
```
but that caused 18 tests to fail for various reasons, so I just removed them from the patch manually.

https://github.com/llvm/llvm-project/pull/86157