Use host's DNS resolver in Docker containers (#812)

* Symlink /etc/resolve.conf to systemd-resolved's stub

Since systemd-resolved is managing the DNS configuration, ensure that
/etc/resolv.conf uses it.

* Use systemd-resolved from Docker containers

migrations/1754984623.sh

@@ -0,0 +1,3 @@
+echo "Ensure DNS resolver configuration is properly symlinked"
+
+sudo ln -sf /run/systemd/resolve/stub-resolv.conf /etc/resolv.conf