s_donation: fix duplicate currency before modifying list

Author: agau-odoo

addons/website_payment/static/src/snippets/s_donation/donation_snippet.js

@@ -44,6 +44,8 @@ export class DonationSnippet extends Interaction {
     start() {
         const prefilledButtonEls = this.el.querySelectorAll(".s_donation_btn, .s_range_bubble");
         for (const prefilledButtonEl of prefilledButtonEls) {
+            // Remove existing currency
+            prefilledButtonEl.querySelector(".s_donation_currency")?.remove();
             const insertBefore = this.currency.position === "before";
             const currencyEl = document.createElement("span");
             currencyEl.innerText = this.currency.symbol;