[llvm] [InstCombine] Transform `vector.reduce.add` and `splat` into multiplication (PR #161020)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-ppc64le-linux-multistage` running on `ppc64le-clang-multistage-test` while building `llvm` at step 11 "ninja check 2".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/76/builds/13019

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

```
Step 11 (ninja check 2) failure: 1200 seconds without output running [b'ninja', b'check-all'], attempting to kill
...
PASS: ThreadSanitizer-powerpc64le :: restore_stack.cpp (102123 of 102137)
PASS: mlgo-utils :: corpus/extract_ir_script.test (102124 of 102137)
PASS: LLVM :: CodeGen/AMDGPU/elf-header-flags-mach.ll (102125 of 102137)
PASS: LLVM :: CodeGen/X86/cpus-intel.ll (102126 of 102137)
PASS: LLVM :: CodeGen/AMDGPU/directive-amdgcn-target.ll (102127 of 102137)
PASS: SanitizerCommon-lsan-powerpc64le-Linux :: Linux/signal_segv_handler.cpp (102128 of 102137)
PASS: SanitizerCommon-asan-powerpc64le-Linux :: Linux/signal_segv_handler.cpp (102129 of 102137)
PASS: SanitizerCommon-msan-powerpc64le-Linux :: Linux/signal_segv_handler.cpp (102130 of 102137)
PASS: SanitizerCommon-tsan-powerpc64le-Linux :: Linux/signal_segv_handler.cpp (102131 of 102137)
PASS: SanitizerCommon-ubsan-powerpc64le-Linux :: Linux/signal_segv_handler.cpp (102132 of 102137)
command timed out: 1200 seconds without output running [b'ninja', b'check-all'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=6144.902318

```

</details>

https://github.com/llvm/llvm-project/pull/161020