lib/installation: Don't try to find dynamic remotes when not needed
lib/installation: Don't try to find dynamic remotes when not needed

When getting the dynamic remotes for the installed refs, if no refs
with a collection ID are found, then the ostree_repo_find_remotes_async
is given an array with just NULL, which makes it early return and thus
it would result in an infinite loop in
flatpak_installation_list_installed_refs_for_update.

This patch only tries to find the dynamic remotes when there are such
refs, thus preventing the mentioned error and any extra unnecessary
processing.

Closes: #1587
Approved by: mwleeds

flatpak/flatpak,flatpak/flatpak,matthiasclasen/flatpak,flatpak/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,flatpak/flatpak,flatpak/flatpak