[llvm] [llvm-symbolizer] nfc, use map instead of vector (PR #69552)

[Chen Zheng via llvm-commits]

chenzheng1030 wrote:

Thanks for review @jh7370 @spavloff .

To address latest comment from @jh7370 , there is no need to refactor the container for symbols. So I directly fix this in XCOFF related patch https://github.com/llvm/llvm-project/pull/69553

Abandon this patch

https://github.com/llvm/llvm-project/pull/69552