[lldb] [llvm] [lldb] Refactor string manipulation in Debugger.cpp (#91209) (PR #91880)

[Youngsuk Kim via llvm-commits]

JOE1994 wrote:

A new user already asked to be assigned to work on #91209 2 days ago in the comments.
**I think that user deserves an opportunity to work on the issue**.

Next time when you see a **"good first issue"** which a new user had already asked to get assigned to,
please assign it to the new user.

https://github.com/llvm/llvm-project/pull/91880