Merged stable into default after publication of Production testing

This new mode of operation was developped on the stable branch of
the tests, because we want to use it on instances running the
current stable Heptapod series (0.19).

The important refactor of the `heptapod.users` values was done
as part of the effort.

Obviously we also want all of this in the default branch.

Took care of keeping the target image correct in CI configuration.
6 jobs for branch/default in 22 minutes and 40 seconds
Status Job ID Name Coverage
  Test Heptapod
passed docker-inside #168045

00:19:12

passed docker-native-inside #168048

00:18:10

passed docker-native-remote-0 #168049

00:18:45

passed docker-native-remote-1 #168050

00:20:53

passed docker-remote-0 #168046

00:18:47

passed docker-remote-1 #168047

00:22:40