[AE-1142] Include ad client dma in the interaction and request-stats pings

[mashalifshin]

Tickets or other relevant links:

https://mozilla-hub.atlassian.net/browse/AE-1142

What's Here

In preparation for rolling out OHTTP between Desktop FFox and MARS, we need to capture all the ad client's geo fields in all our pings -- specifically the interaction and request-stats ping.

Things I'd Like Feedback On

Lmk if you see any issues with capturing this. Looks like it is already available in the backend.

Testing

This can be tested via the companion PR in MARS that use the updated pings structure, see the Testing section there.

Any concerns with backwards compatibility?

No, these changes are additive.

[gleonard-m]

Was a data collection review created for this?

[mashalifshin]

Was a data collection review created for this?

No I didn't do a data review for this change, is it needed? My thought was we're already collecting this data in other pings, and in some cases in other fields of the same ping, but I'm happy to kick that off now if necessary

[mashalifshin]

DATA REVIEW REQUEST

1. What questions will you answer with this data?

In preparation for fully rolling out OHTTP between Desktop FFox and MARS, we need to capture some coarse geo info about the ad client in all our pings, since we will no longer be able to rely on the client's IP address to derive this data. We were already capturing the CountryCode and the RegionCode in interaction and request-stats, this change adds capturing the DMA. (provider-request-stats already captures all three geo info fields).

2. Why does Mozilla need to answer these questions? Are there benefits for users?
   Do we need this information to address product or business requirements?

When we make requests to ad providers, we need to let the ad server know roughly what area the client is coming from so that only relevant ads are returned. So in the case of the request-stats ping, we record for system observability and correctness. In the case of the interaction ping, we record for those same reasons, and for our ad business reporting internally.

3. What alternative methods did you consider to answer these questions?
   Why were they not sufficient?

With the introduction of OHTTP between FFox Desktop and MARS, we no longer have the X-Forwarded-For ip_address field that we used to have in the standard glean ingestion. We are replacing that with three explicit geo metrics, CountryCode, RegionCode, and DMACode. This change completes the third geo metric. (This answer is based on some preliminary conversations in #glean, summarized in https://mozilla-hub.atlassian.net/browse/AE-1142)

4. Can current instrumentation answer these questions?

Soon it won't be able to, so this change shores up our preparation for OHTTP across the metrics we collect.

5. List all proposed measurements and indicate the category of data collection for each
   measurement, using the Firefox data collection categories found on the Mozilla wiki.

Measurement Name	Measurement Description	Data Collection Category	Tracking Bug
ad.dma_code	Designated Marketing Area code (US only) associated with the client when the ad was requested. DMAs are a pre-defined set of city or metro-level regions. May be null.	WIP...	https://mozilla-hub.atlassian.net/browse/AE-1142

6. Please provide a link to the documentation for this data collection which
   describes the ultimate data set in a public, complete, and accurate way.

This collection is Glean so is documented in the Glean Dictionary.

7. How long will this data be collected?

This collection will be collected permanently.
mlifshin@mozilla.com will be responsible for the permanent collections.

8. What populations will you measure?

All channels, countries, and locales. No filters.

9. If this data collection is default on, what is the opt-out mechanism for users?

These collections are Glean. The opt-out can be found in the product's preferences.

10. Please provide a general description of how you will analyze this data.

This data will be part of standard ad reporting for observability, correctness of ad targeting, and as internal business metrics to understand the coarse geo info of where ads are being requested from and returned.

11. Where do you intend to share the results of your analysis?

This data will surface in standard dashboards for ad interactions (impression and click data tables), and MozAds team will use this to understand revenue/business insights.

12. Is there a third-party tool (i.e. not Glean or Telemetry) that you
    are proposing to use for this data collection?

No.

[mashalifshin]

Sensitive Data Review Team has given us the go-ahead to move forward with this change.