revert md widget old click

The MarkdownViewer no longer crahses on external link, but behvaiour with opens remains

Author: lowekoz

src/textual/widgets/_markdown.py

@@ -800,7 +800,7 @@ async def _on_mount(self, _: Mount) -> None:
             await self.update(self._markdown)
 
     def on_markdown_link_clicked(self, event: LinkClicked) -> None:
-        if self.is_external_link(event.href) and self._open_links:
+        if self._open_links:
             self.app.open_url(event.href)
 
     def _watch_code_dark_theme(self) -> None: