feat(media): 图片占位改为纯色块并去掉扫光

lib/pages/new_releases/new_releases_page.dart

@@ -276,7 +276,6 @@ class _NewReleasesPageState extends State<NewReleasesPage> {
               RemoteImage(
                 drama.posterUrl,
                 fit: BoxFit.cover,
-                showFallbackIcon: true,
                 fallbackAspectRatio: 16 / 9,
               ),
               const DecoratedBox(
@@ -448,7 +447,6 @@ class _NewReleasesPageState extends State<NewReleasesPage> {
                     RemoteImage(
                       drama.posterUrl,
                       fit: BoxFit.cover,
-                      showFallbackIcon: true,
                       fallbackAspectRatio: 3 / 4,
                     ),
                     Positioned(