Remove user_id from dimension and add it as "metric" in ad views

[ilias1111]

Description & motivation

In essence we are going to treat user_id the same way we treat domain_sessionid_array, as we may have more than one value and this will cause unwanted extra rows.

This could be happening in cases were we have anonmazion on for media package, we dont capture the user id until the user accepts the tracking and then for the same session, ad_id etc we will have 2 ids null and the real one.

Checklist

• I have verified that these changes work locally
• I have updated the README.md (if applicable)
• I have added tests & descriptions to my models (and macros if applicable)
• I have raised a documentation PR if applicable (Link here)

[matus-tomlein]

LGTM but not sure if it's a breaking change? The schema of the table does not change, just that historical data could be processed differently now. Not sure if that is considered breaking though.

[ilias1111]

@agnessnowplow Should we call it a breaking change? Assuming we dont have reports of users having issue with all that, we could expect I guess that we didnt had lot of cases that will be reprocced differently

[agnessnowplow]

I would say the only time past records would be different is if there were duplicates, but it would have resulted in an error right away (we also have a dbt test on uniqueness) so I don't consider this a breaking change.