Switch replication URL to HTTPS

[russss]

The discussion about moving OSM services to HTTPS-only continues. Although everything should be happy following 302 redirects I thought I'd remove one variable and move the default URL to HTTPS.

Seems to work fine for me.

[bdon]

@russss unrelated to imposm3, can you link me to any discussion on SSL for planet.openstreetmap.org ? I have another replication process that has intermittent problems validating the LetsEncrypt certificate used by planet.openstreetmap.org

[russss]

There is some discussion in openstreetmap/operations#117, and there's also been some chat on the #osm-dev IRC channel over the last week.

[olt]

Thanks!