Fix step-runner inject container run
What does this MR do?
!5322 (merged) was recently merged that added steps-runner injection to the build container.
This fixes a few problems with the container setup and execution, that only become apparent with a remote docker daemon where latency was present.
Why was this MR needed?
- Step-runner container was executing predefined scripts and it doesn't need to do that.
- Container was being removed immediately, which differs from our other containers, and this was unexpected. This was only noticeable due to the latency between requests.
- Added a little context to error messages that helped me determine what was going on.