Consolidate web-connectivity test helper patterns and hosts

[hellais]

Currently we have several VMs running for the web-connectivity test-helper which are deploying using different patterns.

The docker based ones which sometimes go down due to: ooni/sysadmin#128 and the ones without docker.

We should upgrade to using just the pattern without docker and consolidate them all on 2 hosts which are located in amsterdam: ams-wcth2 and ams-wcth3.

[hellais]

I have removed from the inventory mia-wcth.ooni.nu and hkg-wcth.ooni.nu. The VMs have been stopped in the eclipsis web portal in case @FedericoCeratto would like to backup the logs and do something with them.

If no action is taken on them, they will be deleted in 1 month from now.

For some reason ams-wcth.ooni.nu is still receiving a little bit of traffic, but it's unclear from where. @bassosimone can you check if some of the apps have hardcoded as the address of a web-connectivity test-helper ams-wcth.ooni.nu?

[hellais]

I migrated that last point to a new issue and assigned it to myself and @bassosimone for the next sprint: #309.