Failed to load `favicon.ico` in local dev

Given the simplest of Apollo Server instances, run Sandbox and inspect the browser's logs for:
> Failed to load resource: the server responded with a status of 400 (Bad Request)
> :4000/favicon.ico:1

Repro:
```sh
npm init -y
npm i @apollo/server graphql
touch index.js
```

```js
// index.js
import { ApolloServer } from "@apollo/server";
import { startStandaloneServer } from "@apollo/server/standalone";

const server = new ApolloServer({
typeDefs: `#graphql
type Query {
hello: String
}
`,
});

startStandaloneServer(server, { listen: { port: 4000 } }).then(() => {
console.log("Server running at http://localhost:4000");
});
```

```sh
node index.js
```

Reproduce the report with the supplied npm setup, index.js, and node index.js command, then inspect the browser logs for the /favicon.ico 400 response. Trace how the local Sandbox request is handled and consider the issue complete when the favicon request no longer produces the reported 400 error.

Written by the indexing model from the issue text.