[iOS] Fixing signin interaction coordinator active property

The sign-in interaction coordinator is active when it is used with
the sign-in coordinator.

Bug: 971989
Change-Id: Ic199eb9e7628d6f4195f7bbc5637827eccc38cfc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2077933
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Auto-Submit: Jérôme Lebel <jlebel@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745045}

ios/chrome/browser/ui/signin_interaction/signin_interaction_coordinator.mm

@@ -157,7 +157,7 @@
 #pragma mark - Properties
 
 - (BOOL)isActive {
-  return self.controller != nil || self.isSettingsViewPresented;
+  return self.controller != nil || self.coordinator != nil;
 }
 
 - (BOOL)isSettingsViewPresented {