Caching on gateway LocalGraphQLDataSource level does not seem to work

### Issue Description

I am running into an issue where the apollo supergraph's caching does not work, but the underlying supgraphs just work fine.

When executing
```
query a {
foo
}
```
I get response header `cache-control: no-store`

When executing
```
query b {
products {
name
}
}

```
I get response header `cache-control: max-age=500, public`

When executing
```
query c {
foo
products {
name
}
}
```
I get response header `cache-control: max-age=500, public`

Problem 1: I cannot seem to make the cache work for query foo
Problem 2: When querying foo with any other cached subgraph query, it just applies the cacheControl of that query to the whole response, but IMO it should compute the correct restrictive one.

### Link to Reproduction

https://codesandbox.io/p/devbox/headless-cherry-2xpp5d

### Reproduction Steps

```
query c {
foo
}
```

Start by running the linked CodeSandbox reproduction and its three queries, comparing the cache-control headers for foo, products, and their combination. Trace the gateway's LocalGraphQLDataSource caching path to determine why foo is no-store and why mixed responses do not use the restrictive policy. Done means the reproduction shows appropriate caching for foo and the combined query reports the correct restrictive cache-control header.

Written by the indexing model from the issue text.