Finish removing git repository state and scanning logic from worktrees (#27568)

This PR completes the process of moving git repository state storage and
scanning logic from the worktree crate to `project::git_store`.

Release Notes:

- N/A

---------

Co-authored-by: Max Brunsfeld <maxbrunsfeld@gmail.com>
Co-authored-by: Conrad <conrad@zed.dev>

crates/collab/src/tests/integration_tests.rs

@@ -2898,8 +2898,8 @@ async fn test_git_branch_name(
         assert_eq!(
             repository
                 .read(cx)
-                .repository_entry
-                .branch()
+                .branch
+                .as_ref()
                 .map(|branch| branch.name.to_string()),
             branch_name
         )
@@ -3033,7 +3033,6 @@ async fn test_git_status_sync(
         let repo = repos.into_iter().next().unwrap();
         assert_eq!(
             repo.read(cx)
-                .repository_entry
                 .status_for_path(&file.into())
                 .map(|entry| entry.status),
             status
@@ -6882,7 +6881,8 @@ async fn test_remote_git_branches(
                 .next()
                 .unwrap()
                 .read(cx)
-                .current_branch()
+                .branch
+                .as_ref()
                 .unwrap()
                 .clone()
         })
@@ -6919,7 +6919,8 @@ async fn test_remote_git_branches(
                 .next()
                 .unwrap()
                 .read(cx)
-                .current_branch()
+                .branch
+                .as_ref()
                 .unwrap()
                 .clone()
         })