[llvm] [lldb] Add lldb team to CODEOWNERS (PR #65454)

[David Spickett via llvm-commits]

DavidSpickett wrote:

Looking at the diff page I see:
```
Unknown owner on line 622: make sure the team @llvm/pr-subscribers-lldb exists, is publicly visible, and has write access to the repository
/lldb/** @llvm/pr-subscribers-lldb
```
Is that expected? It doesn't say this for any of the existing lines, maybe this team is configured incorrectly.

https://github.com/llvm/llvm-project/pull/65454