[llvm] [Utils] Fix duplicate DomTree updates in SplitIndirectBrCriticalEdges (PR #196475)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

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

Full details are available at: https://lab.llvm.org/buildbot/#/builders/157/builds/46551

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

```
Step 6 (test-build-unified-tree-check-flang) failure: 1200 seconds without output running [b'ninja', b'check-flang'], attempting to kill
...
PASS: Flang :: Semantics/numeric_storage_size.f90 (4452 of 4462)
PASS: Flang :: Transforms/simplify-fir-operations.fir (4453 of 4462)
PASS: Flang :: Semantics/modfile73.f90 (4454 of 4462)
PASS: Flang :: Driver/fopenmp.f90 (4455 of 4462)
PASS: Flang :: Transforms/tbaa-local-alloc-threshold.fir (4456 of 4462)
PASS: Flang :: Transforms/OpenACC/acc-implicit-data-fortran.F90 (4457 of 4462)
PASS: Flang :: Transforms/debug-dwarf-version.fir (4458 of 4462)
PASS: Flang :: Transforms/vscale-attr.fir (4459 of 4462)
PASS: Flang :: Driver/linker-options.f90 (4460 of 4462)
PASS: Flang :: Driver/omp-driver-offload.f90 (4461 of 4462)
command timed out: 1200 seconds without output running [b'ninja', b'check-flang'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=2425.254842

```

</details>

https://github.com/llvm/llvm-project/pull/196475