Remove ASCII art from mDNS error log (flutter#21397)

Author: jmagman

shell/platform/darwin/ios/framework/Source/FlutterObservatoryPublisher.mm

@@ -114,19 +114,16 @@ - (void)publishServiceProtocolPort:(NSString*)uri {
   if (err != 0) {
     FML_LOG(ERROR) << "Failed to register observatory port with mDNS with error " << err << ".";
     if (@available(iOS 14.0, *)) {
-      FML_LOG(ERROR)
-          << "▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒\n"
-          << "On iOS 14+, local network broadcast in apps need to be declared in "
-          << "the app's Info.plist. Debug and profile Flutter apps and modules host "
-          << "VM services on the local network to support debugging features such "
-          << "as hot reload and DevTools.\n\nTo make your Flutter app or module "
-          << "attachable and debuggable, add a '" << registrationType << "' value "
-          << "to the 'NSBonjourServices' key in your Info.plist for the Debug/"
-          << "Profile configurations.\n\n"
-          << "For more information, see "
-          // Update link to a specific header as needed.
-          << "https://flutter.dev/docs/development/add-to-app/ios/project-setup"
-          << "\n▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒";
+      FML_LOG(ERROR) << "On iOS 14+, local network broadcast in apps need to be declared in "
+                     << "the app's Info.plist. Debug and profile Flutter apps and modules host "
+                     << "VM services on the local network to support debugging features such "
+                     << "as hot reload and DevTools. To make your Flutter app or module "
+                     << "attachable and debuggable, add a '" << registrationType << "' value "
+                     << "to the 'NSBonjourServices' key in your Info.plist for the Debug/"
+                     << "Profile configurations. "
+                     << "For more information, see "
+                     // Update link to a specific header as needed.
+                     << "https://flutter.dev/docs/development/add-to-app/ios/project-setup";
     }
   } else {
     DNSServiceSetDispatchQueue(_dnsServiceRef, dispatch_get_main_queue());