Revert "Avoid installing Flapak apps"

This reverts commits 2e85340b and aaa22d6e re enabling the installation of Flatpaks apps. The original problem is caused by HTTP 2 request not being retried by ostree, and the new version can workaround it using HTTP 1.1.

Also apply the workaroud disabling HTTP 2.

See pkg/ostree!28 (merged).

Signed-off-by: Walter Lozano walter.lozano@collabora.com