cherry pick bacd call fix & clean

Session/Calls/Call Management/SessionCallManager.swift

@@ -136,6 +136,10 @@ public final class SessionCallManager: NSObject, CallManagerProtocol {
         func handleCallEnded() {
             WebRTCSession.current = nil
             UserDefaults.sharedLokiProject?.set(false, forKey: "isCallOngoing")
+            if CurrentAppContext().isInBackground() {
+                (UIApplication.shared.delegate as? AppDelegate)?.stopPollers()
+                DDLog.flushLog()
+            }
         }
         
         guard let call = currentCall else {

Session/Meta/AppDelegate.swift

@@ -33,6 +33,7 @@ class AppDelegate: UIResponder, UIApplicationDelegate, UNUserNotificationCenterD
 
         Cryptography.seedRandom()
         AppVersion.sharedInstance()
+        AppEnvironment.shared.pushRegistrationManager.createVoipRegistryIfNecessary()
 
         // Prevent the device from sleeping during database view async registration
         // (e.g. long database upgrades).

Session/Notifications/PushRegistrationManager.swift

@@ -173,7 +173,7 @@ public enum PushRegistrationError: Error {
         }
     }
     
-    private func createVoipRegistryIfNecessary() {
+    public func createVoipRegistryIfNecessary() {
         AssertIsOnMainThread()
 
         guard voipRegistry == nil else { return }