remove redundant orientation detection (#2178)

Task/Issue URL: https://app.asana.com/0/414709148257752/1205887735214021/f
Tech Design URL:
CC:

Description:

Fix text selection bug.

DuckDuckGo/MainViewController.swift

@@ -250,7 +250,6 @@ class MainViewController: UIViewController {
         registerForApplicationEvents()
         registerForCookiesManagedNotification()
         registerForSettingsChangeNotifications()
-        registerForOrientationChangeNotification()
 
         tabManager.cleanupTabsFaviconCache()
 
@@ -276,17 +275,6 @@ class MainViewController: UIViewController {
         super.performSegue(withIdentifier: identifier, sender: sender)
     }
 
-    func registerForOrientationChangeNotification() {
-        NotificationCenter.default.addObserver(self,
-                                               selector: #selector(orientationDidChange),
-                                               name: UIDevice.orientationDidChangeNotification,
-                                               object: nil)
-    }
-
-    @objc func orientationDidChange() {
-        onAddressBarPositionChanged()
-    }
-
     func loadSuggestionTray() {
         let storyboard = UIStoryboard(name: "SuggestionTray", bundle: nil)