fix(seed): registration uses image name without tag

[armandobelardo]

We now use a tagless docker image name when registering the generators

This wasn't an issue because we weren't using the image lookup endpoint, but now that we're starting to, this fix is necessary

Summary

This pull request makes a minor change to the registerGenerator function in the registerGenerator.ts file.

Changes

• The dockerImage parameter is now set to generatorConfig.image instead of generatorConfig.test.docker.image.
• The log message has been updated to "Registration complete."