Fix email content is broken when perform previous/next email then back to app (#4028)

lib/features/thread_detail/presentation/extension/get_thread_details_email_views.dart

@@ -69,7 +69,6 @@ extension GetThreadDetailEmailViews on ThreadDetailController {
         return Padding(
           padding: const EdgeInsetsDirectional.only(bottom: 16),
           child: EmailView(
-            key: GlobalObjectKey('${presentationEmail.id?.id.value ?? ''}firstInThread'),
             isInsideThreadDetailView: true,
             emailId: presentationEmail.id,
             isFirstEmailInThreadDetail: true,
@@ -85,7 +84,6 @@ extension GetThreadDetailEmailViews on ThreadDetailController {
       return Padding(
         padding: const EdgeInsetsDirectional.only(bottom: 16),
         child: EmailView(
-          key: GlobalObjectKey(presentationEmail.id?.id.value ?? ''),
           isInsideThreadDetailView: true,
           emailId: presentationEmail.id,
           onToggleThreadDetailCollapseExpand: () {

lib/features/thread_detail/presentation/thread_detail_view.dart

@@ -136,9 +136,6 @@ class ThreadDetailView extends GetWidget<ThreadDetailController> {
                         ? manager.availableThreadIds.length
                         : manager.currentDisplayedEmails.length,
                     itemBuilder: (context, index) {
-                      if (index != currentIndex) {
-                        return const SizedBox.shrink();
-                      }
                       return SingleChildScrollView(child: threadBody);
                     },
                     onPageChanged: controller.onThreadPageChanged,