[clang-tools-extra] [clang-doc] concatenate SymbolIDs to truncated mangled names (PR #159490)

[Erick Velez via cfe-commits]

evelez7 wrote:

### Merge activity

* **Sep 23, 5:22 PM UTC**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/159490).


https://github.com/llvm/llvm-project/pull/159490