Fix test nesting structure to resolve CI failures

- Removed premature closing brace in 'Channel links' describe block
- Properly nested the new test 'should link ~town-square with team context from post props'
- Fixes TypeScript syntax errors and test parsing failures

webapp/channels/src/utils/text_formatting_channel_links.test.ts

@@ -81,7 +81,6 @@ describe('TextFormatting.ChannelLinks', () => {
                 '<p>(<a class="mention-link" href="/myteam/channels/town-square" data-channel-mention="town-square">~Town Square</a>)</p>',
             );
         });
-    });
 
         test('should link ~town-square with team context from post props', () => {
             expect(