Avoid creating unnecessary temporary cat file sub process (#33942)

Extract from #33934 

In the same goroutine, we should reuse the exist cat file sub process
which exist in `git.Repository` to avoid creating a unnecessary
temporary subprocess.

This PR reuse the exist cate file writer and reader in
`getCommitFromBatchReader`.
It also move `prepareLatestCommitInfo` before creating dataRc which will
hold the writer so other git operation will create a temporary cat file
subprocess.

modules/repository/repo.go

@@ -126,7 +126,7 @@ func PushUpdateAddTag(ctx context.Context, repo *repo_model.Repository, gitRepo
 	if err != nil {
 		return fmt.Errorf("unable to GetTag: %w", err)
 	}
-	commit, err := tag.Commit(gitRepo)
+	commit, err := gitRepo.GetTagCommit(tag.Name)
 	if err != nil {
 		return fmt.Errorf("unable to get tag Commit: %w", err)
 	}