collab: Fix project sharing between Windows and Unix (#23680)

Closes #14258

Windows user(host) sharing a project to a guest(using macOS), and host
follows guest:


https://github.com/user-attachments/assets/ba306b6b-23f7-48b1-8ba8-fdc5992d8f00

macOS user(host) sharing a project to a guest(using Windows), and host
follows guest:



https://github.com/user-attachments/assets/c5ee5e78-870d-49e5-907d-8565977a01ae

macOS user edits files in a windows project through collab:



https://github.com/user-attachments/assets/581057cf-e7df-4e56-a0ce-ced74339906a





Release Notes:

- N/A

crates/git/src/repository.rs

@@ -571,10 +571,6 @@ impl RepoPath {
 
         RepoPath(path.into())
     }
-
-    pub fn to_proto(&self) -> String {
-        self.0.to_string_lossy().to_string()
-    }
 }
 
 impl std::fmt::Display for RepoPath {