docs(material/autocomplete): use single map instead of two maps in a row (#25167)

* docs(material/autocomplete): use single map instead of two maps in a row

The example code is highly trusted and sometimes
taken as is (copy-paste), so it is important to
have it optimized if possible.
Each map means an iteration over the array items.
By using single map, an iteration is saved, and
an approximate performance of about 38% is won.

* docs(material/autocomplete): add trailing comma

Author: ammarnajjar

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

@@ -23,8 +23,10 @@ export class AutocompleteDisplayExample implements OnInit {
   ngOnInit() {
     this.filteredOptions = this.myControl.valueChanges.pipe(
       startWith(''),
-      map(value => (typeof value === 'string' ? value : value?.name)),
-      map(name => (name ? this._filter(name) : this.options.slice())),
+      map(value => {
+        const name = typeof value === 'string' ? value : value?.name;
+        return name ? this._filter(name as string) : this.options.slice();
+      }),
     );
   }