feat(portalmigrations): enable seeding of test data with configmap

[evegufy]

Description

• enable seeding of test data with configmap

and move default seeding path and processidentity userid out of values file, into job, as changing those values isn't intuitive

Why

https://github.com/eclipse-tractusx/tractus-x-umbrella/issues/105

Checklist

• [x] I have performed a self-review of my changes
• [x] I have successfully tested my changes
• [x] I have added comments in the default values.yaml file with helm-docs syntax ('# -- ') if relevant for installation