docs(material/chips): remove unused field in the autocomplete example (#22958)

Author: AlexElin

src/components-examples/material/chips/chips-autocomplete/chips-autocomplete-example.ts

@@ -1,7 +1,7 @@
 import {COMMA, ENTER} from '@angular/cdk/keycodes';
 import {Component, ElementRef, ViewChild} from '@angular/core';
 import {FormControl} from '@angular/forms';
-import {MatAutocompleteSelectedEvent, MatAutocomplete} from '@angular/material/autocomplete';
+import {MatAutocompleteSelectedEvent} from '@angular/material/autocomplete';
 import {MatChipInputEvent} from '@angular/material/chips';
 import {Observable} from 'rxjs';
 import {map, startWith} from 'rxjs/operators';
@@ -25,7 +25,6 @@ export class ChipsAutocompleteExample {
   allFruits: string[] = ['Apple', 'Lemon', 'Lime', 'Orange', 'Strawberry'];
 
   @ViewChild('fruitInput') fruitInput: ElementRef<HTMLInputElement>;
-  @ViewChild('auto') matAutocomplete: MatAutocomplete;
 
   constructor() {
     this.filteredFruits = this.fruitCtrl.valueChanges.pipe(