build: remove unused animation definition from docs site

Removes an animation definition that wasn't being used anywhere in the docs.

Author: crisbeto

material.angular.io/src/app/pages/component-sidenav/component-sidenav.ts

@@ -9,7 +9,6 @@ import {
   input,
   viewChild,
 } from '@angular/core';
-import {animate, state, style, transition, trigger} from '@angular/animations';
 import {CdkAccordionModule} from '@angular/cdk/accordion';
 import {BreakpointObserver} from '@angular/cdk/layout';
 import {AsyncPipe} from '@angular/common';
@@ -127,13 +126,6 @@ export class ComponentSidenav implements OnInit, OnDestroy {
 @Component({
   selector: 'app-component-nav',
   templateUrl: './component-nav.html',
-  animations: [
-    trigger('bodyExpansion', [
-      state('collapsed', style({height: '0px', display: 'none'})),
-      state('expanded', style({height: '*', display: 'block'})),
-      transition('expanded <=> collapsed', animate('225ms cubic-bezier(0.4,0.0,0.2,1)')),
-    ]),
-  ],
   standalone: true,
   imports: [MatListModule, RouterLinkActive, RouterLink, AsyncPipe],
 })