Remove the allowedNotificationOrigins PRESERVED_TARGETING_KEYS stopgap once the manifest records it

Blocked. Do not start until the gate below is met.

allowedNotificationOrigins is listed in PRESERVED_TARGETING_KEYS_BY_APPLICATION[Application.DESKTOP] in experimenter/targeting/constants.py. That entry is a stopgap: it lets the has_allowed_notifications targeting config reference an attribute that the in-repo recorded targeting context manifest does not yet contain, so test_validate_targeting_config_fields accepts it.

The attribute itself landed in mozilla-central under bug 2069104, which added the ASRouterTargeting getter, the TargetingContextRecorder.sys.mjs entry and the allowed_notification_origins Glean probe in one commit. Its JEXL-to-SQL column mapping landed separately in #17338.

Gate

An Update External Configs PR has to land the new features/manifests/firefox-desktop/TargetingContextRecorder.sys.mjs, i.e. the copy whose ATTRIBUTE_TRANSFORMS includes allowedNotificationOrigins: typeAssertions.quantity. Check with:

grep -c allowedNotificationOrigins experimenter/experimenter/features/manifests/firefox-desktop/TargetingContextRecorder.sys.mjs

Once that returns non-zero on main, TargetingContextFields.for_application(Application.DESKTOP) resolves the attribute from the manifest and the allowlist entry is redundant.

Acceptance criteria

• The allowedNotificationOrigins entry and its accompanying comment are removed from PRESERVED_TARGETING_KEYS_BY_APPLICATION[Application.DESKTOP].
• test_validate_targeting_config_fields still passes for has_allowed_notifications, resolving the attribute from the manifest rather than the allowlist.
• test_desktop_targeting_context_fields_are_mapped still passes, resolving the attribute via JEXL_TO_BQ_COLUMN.
• make code_format check passes.

┆Issue is synchronized with this Jira Task