Fix Percy static-viz failures on `master` (#28323)

* Fix broken visual tests

* Increase the timeout due to slow webmail interaction

frontend/test/__support__/e2e/helpers/e2e-email-helpers.js

@@ -53,11 +53,13 @@ export const clearInbox = () => {
 };
 
 export const openEmailPage = emailSubject => {
-  cy.window().then(win => (win.location.href = "http://localhost"));
+  const webmailInterface = `http://localhost:${WEB_PORT}`;
+
+  cy.window().then(win => (win.location.href = webmailInterface));
   cy.findByText(emailSubject).click();
 
   return cy.hash().then(path => {
-    const htmlPath = `http://localhost${path.slice(1)}/html`;
+    const htmlPath = `${webmailInterface}${path.slice(1)}/html`;
     cy.window().then(win => (win.location.href = htmlPath));
     cy.findByText(emailSubject);
   });
@@ -65,7 +67,7 @@ export const openEmailPage = emailSubject => {
 
 export const clickSend = () => {
   cy.button("Send email now").click();
-  cy.button("Email sent", 30000);
+  cy.button("Email sent", 60000);
 };
 
 export const sendSubscriptionsEmail = recipient => {