Feature: Builder should cancel workflow after sigterm received and not wait until the whole workflow finishes

[Despire]

Description

Currently when Builder receives the sigterm signal it will finish whatever workflow is being executed (which can range from dozens of minutes up to hours depending on the size of the cluster being build), when a sigterm is recieved builder should only wait for the current step being executed (terraformer, ansibler etc..) and cancel any further steps. The current state should be written to the DB and picked up by the next pod.

The cancelation can be simply achieved by the correct use of context package

Exit criteria

• Make builder exit on sigterm after finishing the current step instead of waiting for the whole workflow
• Save the current state to DB so the next pod can pick it up where the old replica left off.

[Despire]

Duplicate of #1298