Fix QueryManager for queries with fetchPolicy="no-cache"

[bradleyayers]

This PR fixes a bug with fetchPolicy="no-cache", where data initially appears, and then subsequently disappears (e.g. #3452 (comment)). I was able to reproduce the issue:

1. Use InMemoryCache.

2. Make a query with fetchPolicy="no-cache". It will resolve correctly and the data will be available.

3. While that query is still being observed (via ObservableQuery), make a separate query using cache-and-network (I don't think the fetchPolicy is actually significant here).

4. When the new query updates the cache:

   1. QueryManager#broadcastQueries() is called.
   2. A cache watch's callback (which was incorrectly setup when the no-cache query was created) is executed and calls this.setQuery(queryId, () => ({ invalidated: true, newData }));
   3. Because the query isn't in the cache, newData is empty, but the query is updated anyway.
   4. The existing ObservableQuery for the no-cache query has the empty result emitted.

I'm not familiar enough with this codebase to know how to write a test for this, so it'd be great if someone else could jump in and help with that.

Relates to #3452.

Questions:

1. Why does this.dataStore.getCache().watch({…}) trigger for the no-cache query when a different (unrelated) query updates the cache?

Checklist:

• If this PR is a new feature, please reference an issue where a consensus about the design was reached (not necessary for small changes)
• Make sure all of the significant new logic is covered by tests

[davewthompson]

Can this be fixed? We're seeing issues with it.

[bradleyayers]

@benjamn is there anything else I should be doing with this to move it forward?

[benjamn]

Looks good @bradleyayers; sorry for the delay!