renderer: Remove dead show-network-error message.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

app/renderer/js/main.ts

@@ -957,10 +957,6 @@ class ServerManagerView {
       },
     );
 
-    ipcRenderer.on("show-network-error", (event: Event, index: number) => {
-      this.openNetworkTroubleshooting(index);
-    });
-
     ipcRenderer.on("open-settings", async () => {
       await this.openSettings();
     });