Turn shouldUseHttpsOnly's default to true (fixes tor-browser#41094).

It seems to work as expected (screenshots attached):

1. HTTPS-only is enabled by default and can be switched on/off in settings
2. HTTPS-only kicks in before HTTPS Everywhere (which we're keeping around for now): this users can provide feedback about our goal setup (no HTTPSE) but they're not locked in if they really need to switch back to HTTPS Everywhere.

app/src/main/java/org/mozilla/fenix/utils/Settings.kt

@@ -540,7 +540,7 @@ class Settings(private val appContext: Context) : PreferencesHolder {
 
     var shouldUseHttpsOnly by booleanPreference(
         appContext.getPreferenceKey(R.string.pref_key_https_only),
-        default = false
+        default = true
     )
 
     var shouldUseHttpsOnlyInAllTabs by booleanPreference(