Fix release announcement test flake (#30250)

* chore: add `hideJumpToBottomButton` option to playwright screenshot

* test: hide jump to bottom button in release announcement test

playwright/element-web-test.ts

@@ -107,6 +107,7 @@ interface ExtendedToMatchScreenshotOptions extends ToMatchScreenshotOptions {
     includeDialogBackground?: boolean;
     showTooltips?: boolean;
     timeout?: number;
+    hideJumpToBottomButton?: boolean;
 }
 
 type Expectations = {
@@ -165,6 +166,14 @@ export const expect = baseExpect.extend<Expectations>({
             `;
         }
 
+        if (options?.hideJumpToBottomButton) {
+            css += `
+                .mx_JumpToBottomButton {
+                    display: none !important;
+                }
+            `;
+        }
+
         if (options?.css) {
             css += options.css;
         }