Backport #23372Fix#23357 .
Now the `/repos/{owner}/{repo}/git/notes/{sha}` API supports getting
notes by a ref or sha
(https://try.gitea.io/api/swagger#/repository/repoGetNote). But the
`GetNote` func can only accept commit ID.
a12f575737/modules/git/notes_nogogit.go (L18)
So we need to convert the query parameter to commit ID before calling
`GetNote`.
Co-authored-by: Zettat123 <zettat123@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>