replace Polls history strings with Poll history (#10454)

Co-authored-by: Michael Weimann <michaelw@matrix.org>

test/components/views/dialogs/RoomSettingsDialog-test.tsx

@@ -99,7 +99,7 @@ describe("<RoomSettingsDialog />", () => {
         it("displays poll history when tab clicked", () => {
             const { container } = getComponent();
 
-            fireEvent.click(screen.getByText("Polls history"));
+            fireEvent.click(screen.getByText("Poll history"));
 
             expect(container.querySelector(".mx_SettingsTab")).toMatchSnapshot();
         });

test/components/views/dialogs/__snapshots__/RoomSettingsDialog-test.tsx.snap

@@ -74,7 +74,7 @@ NodeList [
     <span
       class="mx_TabbedView_tabLabel_text"
     >
-      Polls history
+      Poll history
     </span>
   </div>,
 ]
@@ -90,7 +90,7 @@ exports[`<RoomSettingsDialog /> poll history displays poll history when tab clic
     <h2
       class="mx_Heading_h2 mx_PollHistory_header"
     >
-      Polls history
+      Poll history
     </h2>
     <div
       class="mx_PollHistoryList"