[llvm] [RISCV] Add ZVBB RUN lines to vpgather-sdnode.ll and vpscatter-sdnode.ll. NFC (PR #220400)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `ppc64le-mlir-rhel-clang` running on `ppc64le-mlir-rhel-test` while building `llvm` at step 6 "test-build-check-mlir-build-only-check-mlir".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/129/builds/51571

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-check-mlir-build-only-check-mlir) failure: 1200 seconds without output running [b'ninja', b'check-mlir'], attempting to kill
...
PASS: MLIR :: Transforms/test-canonicalize-filter.mlir (4556 of 4565)
PASS: MLIR :: Transforms/test-canonicalize-merge-large-blocks.mlir (4557 of 4565)
PASS: MLIR :: mlir-tblgen/attr-or-type-format.td (4558 of 4565)
PASS: MLIR :: mlir-tblgen/attrdefs.td (4559 of 4565)
PASS: MLIR :: mlir-runner/utils.mlir (4560 of 4565)
PASS: MLIR :: mlir-runner/verify-entry-point.mlir (4561 of 4565)
PASS: MLIR :: mlir-runner/sgemm-naive-codegen.mlir (4562 of 4565)
PASS: MLIR :: mlir-runner/simple.mlir (4563 of 4565)
PASS: MLIR :: mlir-reduce/reduction-tree/reduction-tree.mlir (4564 of 4565)
PASS: MLIR :: mlir-reduce/reduction-tree/simple-test.mlir (4565 of 4565)
command timed out: 1200 seconds without output running [b'ninja', b'check-mlir'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=2532.975333

```

</details>

https://github.com/llvm/llvm-project/pull/220400