[llvm] [ADT] Always use 32-bit size type for SmallVector with 16-bit elements (PR #95536)

[Jakub Kuderski via llvm-commits]

https://github.com/kuhar commented:

Please add some tests for common types like `char`, `int16_t`, etc. (e.g., using `std::is_same_v<T1, T2>`)

https://github.com/llvm/llvm-project/pull/95536