fix(router): Clear internal transition when navigation finalizes (#54261

)

This commit fixes a small memory issue in the router where a destroyed
component instance would be retained.

fixes #54241

PR Close #54261

packages/router/src/navigation_transition.ts

@@ -688,6 +688,7 @@ export class NavigationTransitions {
                            // finalized.
                            if (this.currentNavigation?.id === overallTransitionState.id) {
                              this.currentNavigation = null;
+                             this.currentTransition = null;
                            }
                          }),
                          catchError((e) => {