urlutil: remove usage of `ui.expandpath` in `get_pull_paths`
We want to deprecate `ui.expandpath` and simplify the code before adding more
complexity in the form of `[paths]` entry pointing to multiple url. So we inline
the relevant bits.
Differential Revision: https://phab.mercurial-scm.org/D10429
debugbackupbundle: use `get_unique_pull_path`
This is the last known user of `ui.expandpath` outside of `urlutil`. Hooray.
Differential Revision: https://phab.mercurial-scm.org/D10428