Reduce dependencies on g/g

[unmarshall]

How to categorize this issue?

/area dev-productivity
/area open-source
/kind technical-debt

What would you like to be added:

• Except ImageVectorOverride all other places where we are using g/g utilities should be removed.
• Add constants.go in etcd-druid API and move the reconcile annotation key there. Rename the reconcile annotation key and to maintain backward compatibility continue to support the current reconcile annotation key name.

Why is this needed:

gardener is a mono repo and adding it to the go mod dependencies brings in truck load of dependencies which are not really needed in etcd-druid. We only use utilities from gardener/gardener code base and many of which are very simple ones as well which do not require the entire weight of g/g code base to be added into go mod dependencies.