The initial stages in the donation pipeline have redundant, overly complex logic and configuration for determining which gateway and payment methods to show a user. In-banner JS, Donate Wiki and Payments all have logic for this. We should simplify and consolidate, so that we have harmonized, clear configuration and decision logic that run wherever needed.

See also:

• T136254: [EPIC] Refactor form chooser
• T131989: Form chooser should query gatway capabilities to route donation
• Some GatewayFormChooser documentation