[ads] Only collect, store and redeem essential metadata

[tmancey]

Description

See https://github.com/brave/reviews/issues/1636 > 2.1

• [x] Update README.md documentation

For Rewards users:

• [x] Only collect essential metadata
  • [x] Remove topSegment and countryCode from confirmation token redemption payload
• [x] Remove non-essential ad events
  • [x] Ad events should be purged after 3 months [required for frequency capping, i.e. totalMax]

For non-Rewards users (other than users opted-in to Brave News):

• [x] Only collect essential metadata
  • [x] Search result ad with no conversion url pattern should not be processed by the ads component
• [x] Only store clicked ad events [required for click-through conversions]
• [x] Only redeem essential metadata
  • [x] Do not report viewed impressions
  • [x] Do not report clicks
  • [x] Do not report page lands/site visits
  • [x] Do not report httpResponseStatus in payload
  • [x] Do not report view-through conversions
  • [x] Report click-through conversions (Default conversions only, i.e., not verifiable)
  • [x] Do not report verifiable conversions [already worked as expected]
• [x] Remove non-essential ad events
  • [x] Discard legacy non-clicked ad events during database migration
  • [x] Ad events should be purged after 30 days [required for 1, 7 and 30 day observation windows]
  • [x] Purge Default/ads_service folder when resetting Brave Rewards [already worked as expected]

[diracdeltas]

Ad event history should be purged after 30 days

Should be 1 day or 7 days if those are the conversion intervals

[tmancey]

@diracdeltas conversion intervals are 1, 7 or 30 days. Thanks