DonationSummary: filter 'give_payment_gateway_donation_summary' applied twice

[Genevieve-K]

In src/Framework/PaymentGateways/DonationSummary.php, the getSummaryWithDonor() function applies a filter on the summary. But before the function getSummary() was called with the same filter. I add an information in this description, and this information is added twice.

[JasonTheAdams]

Resolved in #6678