Ensure we are always using the same token setting for datapusher

[avdata99]

It's not clear which token setting is required

This PR:

• Moves all references to the util get_dp_plus_user_apitoken
• Preserve the default ckan.datapusher.api_token and aldo continues using the new setting ckan.datapusher_plus.api_token

I'm not sure which one we expect to use.

Also:

• Small code changes to clean unused imports

[tino097]

Thanks @avdata99

[tino097]

hey @avdata99 i've just noticed that you have ckan.datapusher_plus.api_token but in the config declaration we have set all the config variables as ckanext.datapusher_plus.*** . Not sure why didnt complain

[avdata99]

I think it was before this change @tino097 3152328
In the future we will only use the new setting