multiple use of the same image fix

[shaharpx]

Cleanup phase failed when using the same image for multiple components due to a failure in removing the image
more than once. To fix this - ignored that specific issue "reference does not exist" when that error is returned
from the docker remove request

[avivpxi]

@shaharpx
Lack of conventions on the Go community generates quirky error handling (if i remember correctly, docker does not create proper typing for errors or ways to identify, forcing us to do string contains).
Aside from that, sounds reasonable that if docker still uses the image it won't be deleted and it won't trigger a failure on the envite flow.
Approved

[vladpx]

LGTM