Update dropdown's settings keyboard accelerator (#9294)

Fixes a bug introduced by #9224 where the wrong keyboard accelerator
would appear in the new tab dropdown. We were looking for the "settings
file" version of the action, as opposed to the "settings UI" version. 

## References
#9224 - Settings UI as default
#6800 - Settings UI Epic

src/cascadia/TerminalApp/TerminalPage.cpp

@@ -658,7 +658,7 @@ namespace winrt::TerminalApp::implementation
                 settingsItem.Click({ this, &TerminalPage::_SettingsButtonOnClick });
                 newTabFlyout.Items().Append(settingsItem);
 
-                Microsoft::Terminal::Settings::Model::OpenSettingsArgs args{ SettingsTarget::SettingsFile };
+                Microsoft::Terminal::Settings::Model::OpenSettingsArgs args{ SettingsTarget::SettingsUI };
                 Microsoft::Terminal::Settings::Model::ActionAndArgs settingsAction{ ShortcutAction::OpenSettings, args };
                 const auto settingsKeyChord{ keyBindings.GetKeyBindingForActionWithArgs(settingsAction) };
                 if (settingsKeyChord)