[llvm] [VPlan] Remove VPInstruction::Not. NFC (PR #222228)

[via llvm-commits]

github-actions[bot] wrote:

test-suite diff from 7c4aac7e60f9f813df5693dcc735bda7873594f7...e1e99167c076d60a95b7df7ddf15b7ff4d58cf3d: https://github.com/llvm/llvm-project/actions/runs/34309490989/artifacts/10090179788

Statistics: https://github.com/llvm/llvm-project/actions/runs/34309490989/artifacts/10090180596

## riscv64-linux-gnu `-march=rva23u64 -O3`
| ('Program', '')    |   ('size..text', 'base') |   ('size..text', 'head') |   ('size..text', 'diff') |
|:-------------------|-------------------------:|-------------------------:|-------------------------:|
| Geomean difference |                      nan |                      nan |                        0 |
## aarch64-linux-gnu `-march=armv9-a -O3`
| ('Program', '')    |   ('size..text', 'base') |   ('size..text', 'head') |   ('size..text', 'diff') |
|:-------------------|-------------------------:|-------------------------:|-------------------------:|
| Geomean difference |                      nan |                      nan |                        0 |
## x86_64-linux-gnu `-march=x86-64-v3 -O3`
| ('Program', '')    |   ('size..text', 'base') |   ('size..text', 'head') |   ('size..text', 'diff') |
|:-------------------|-------------------------:|-------------------------:|-------------------------:|
| Geomean difference |                      nan |                      nan |                        0 |


https://github.com/llvm/llvm-project/pull/222228