Remove redundant applicationWillTerminate notification

AppDelegate already does the exact same thing.

Signal/src/util/MainAppContext.m

@@ -62,10 +62,6 @@ NS_ASSUME_NONNULL_BEGIN
                                              selector:@selector(applicationDidBecomeActive:)
                                                  name:UIApplicationDidBecomeActiveNotification
                                                object:nil];
-    [[NSNotificationCenter defaultCenter] addObserver:self
-                                             selector:@selector(applicationWillTerminate:)
-                                                 name:UIApplicationWillTerminateNotification
-                                               object:nil];
 
     // We can't use OWSSingletonAssert() since it uses the app context.
 
@@ -172,14 +168,6 @@ NS_ASSUME_NONNULL_BEGIN
     [self runAppActiveBlocks];
 }
 
-- (void)applicationWillTerminate:(NSNotification *)notification
-{
-    OWSAssertIsOnMainThread();
-
-    OWSLogInfo(@"");
-    OWSLogFlush();
-}
-
 #pragma mark -
 
 - (BOOL)isMainApp