[llvm] [JSON] Consistently reset moved-from object (PR #185125)

[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 3 "clean-build-dir".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/129/builds/40348

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

```
Step 3 (clean-build-dir) failure: Delete failed. (failure) (timed out)
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 :: Dialect/IRDL/testd.irdl.mlir (3924 of 3935)
PASS: MLIR :: Dialect/Linalg/promotion_options.mlir (3925 of 3935)
PASS: MLIR :: Dialect/LLVMIR/nvvm-mma-blockscale.mlir (3926 of 3935)
PASS: MLIR :: Dialect/LLVMIR/use-default-visibility.mlir (3927 of 3935)
PASS: MLIR-Unit :: IR/./MLIRIRTests/104/141 (3928 of 3935)
PASS: MLIR :: Dialect/ControlFlow/ops.mlir (3929 of 3935)
PASS: MLIR-Unit :: IR/./MLIRIRTests/100/141 (3930 of 3935)
PASS: MLIR-Unit :: IR/./MLIRIRTests/101/141 (3931 of 3935)
PASS: MLIR :: mlir-tblgen/llvm-intrinsics.td (3932 of 3935)
PASS: MLIR :: mlir-reduce/dce-test.mlir (3933 of 3935)
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=2392.352189

```

</details>

https://github.com/llvm/llvm-project/pull/185125