build: remove leftover log (#24571)

Cleans up a `console.log` that was accidentally left in as a part of bbe6355.

(cherry picked from commit d8b5665)

Author: crisbeto

src/cdk/overlay/overlay-ref.ts

@@ -437,7 +437,6 @@ export class OverlayRef implements PortalOutlet, OverlayReference {
     // either async or fakeAsync.
     this._backdropTimeout = this._ngZone.runOutsideAngular(() =>
       setTimeout(() => {
-        console.log('fallback');
         this._disposeBackdrop(backdropToDetach);
       }, 500),
     );