chore: still keep ctx in git.Repository struct for cat-file batch command (#38684)

Unfortunately, we can't completely remove the ctx from git.Repository,
because the CatFileBatch still heavily depends on a parent context.

If we remove the Repository ctx, the CatFileBatch will become a mess and
create a lot of unnecessary git processes.

http://localhost:3000/-/admin/monitor/perftrace

* Before: open a repo home, dozens of git processes (duplicate cat-file)
* After: only a few (no duplicate cat-file)

services/contexttest/context_tests.go

@@ -140,7 +140,7 @@ func LoadRepoCommit(t *testing.T, ctx gocontext.Context) {
 		assert.FailNow(t, "context is not *context.Context or *context.APIContext")
 	}
 
-	gitRepo, err := git_module.OpenRepository(repo.Repository)
+	gitRepo, err := git_module.OpenRepository(ctx, repo.Repository)
 	require.NoError(t, err)
 	t.Cleanup(func() {
 		gitRepo.Close()
@@ -184,7 +184,7 @@ func LoadGitRepo(t *testing.T, ctx gocontext.Context) {
 	}
 	assert.NoError(t, repo.Repository.LoadOwner(ctx))
 	var err error
-	repo.GitRepo, err = git_module.OpenRepository(repo.Repository)
+	repo.GitRepo, err = git_module.OpenRepository(ctx, repo.Repository)
 	assert.NoError(t, err)
 }