Improve image ID logging in job trace

When image's ID is used as it's name (e.g. for predefined containers) we should skip the ID=sha256:.... part of the log line.

So this

Using docker image sha256:e2ffd258d39f1f5688eb895fca85b74374a587ee560c8ac91e39b8418c24cbc3 ID=sha256:e2ffd258d39f1f5688eb895fca85b74374a587ee560c8ac91e39b8418c24cbc3 for predefined container...

would look like this:

Using docker image sha256:e2ffd258d39f1f5688eb895fca85b74374a587ee560c8ac91e39b8418c24cbc3 for predefined container...