Clean up Windows plugin template (#70403)

Removes a comment that is left over from early iterations of the
template.

packages/flutter_tools/templates/plugin/windows.tmpl/pluginClassSnakeCase.cpp.tmpl

@@ -56,12 +56,6 @@ void {{pluginClass}}::RegisterWithRegistrar(
 void {{pluginClass}}::HandleMethodCall(
     const flutter::MethodCall<flutter::EncodableValue> &method_call,
     std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result) {
-  // Replace "getPlatformVersion" check with your plugin's method.
-  // See:
-  // https://github.com/flutter/engine/tree/master/shell/platform/common/cpp/client_wrapper/include/flutter
-  // and
-  // https://github.com/flutter/engine/tree/master/shell/platform/glfw/client_wrapper/include/flutter
-  // for the relevant Flutter APIs.
   if (method_call.method_name().compare("getPlatformVersion") == 0) {
     std::ostringstream version_stream;
     version_stream << "Windows ";