Change when the build is considered finished

[jsnjack]

At the moment there are 2 main tasks categories - main and the rest. When all main tasks are done wake signals that build is finished and keeps executing the rest of the tasks. Initial idea behind this was that all important stuff is done by main tasks and some unimportant (like sending notifications, clean ups) by the rest of them.

However, we have jobs when important tasks are done by the rest tasks (image publishing) and takes some time (about 30s). Marking the build as finished is confusing