msglist test: Remove redundant regression test.

A test on CombinedFeedNarrow is sufficient for preventing this particular
regression. We could go further and test this on other narrows, but
there is little to gain other than verifying that those other narrows do
not have a compose box, which is covered statically with the exhaustive
check from hasComposeBox.

Signed-off-by: Zixuan James Li <[email protected]>

Author: PIG208

test/widgets/message_list_test.dart

@@ -135,19 +135,6 @@ void main() {
       final padding = MediaQuery.of(element).padding;
       check(padding).equals(EdgeInsets.zero);
     });
-
-    testWidgets('content in MentionsNarrow not asked to consume insets (including bottom)', (tester) async {
-      const fakePadding = FakeViewPadding(left: 10, top: 10, right: 10, bottom: 10);
-      tester.view.viewInsets = fakePadding;
-      tester.view.padding = fakePadding;
-
-      await setupMessageListPage(tester, narrow: const MentionsNarrow(),
-        messages: [eg.streamMessage(content: ContentExample.codeBlockPlain.html, flags: [MessageFlag.mentioned])]);
-
-      final element = tester.element(find.byType(CodeBlock));
-      final padding = MediaQuery.of(element).padding;
-      check(padding).equals(EdgeInsets.zero);
-    });
   });
 
   testWidgets('smoke test for light/dark/lerped', (tester) async {