[llvm] [ADT] Remove #include <limits> in RadixTree.h (NFC) (PR #165115)

[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/32197

<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 4 (cmake-configure) failure: cmake (failure) (timed out)
command timed out: 1200 seconds without output running [b'cmake', b'-DLLVM_TARGETS_TO_BUILD=PowerPC', b'-DLLVM_INSTALL_UTILS=ON', b'-DCMAKE_CXX_STANDARD=17', b'-DLLVM_ENABLE_PROJECTS=mlir', b'-DLLVM_LIT_ARGS=-vj 256', b'-DCMAKE_C_COMPILER_LAUNCHER=ccache', b'-DCMAKE_CXX_COMPILER_LAUNCHER=ccache', b'-DCMAKE_BUILD_TYPE=Release', b'-DLLVM_ENABLE_ASSERTIONS=ON', b'-GNinja', b'../llvm-project/llvm'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=1200.797160

```

</details>

https://github.com/llvm/llvm-project/pull/165115