ObservableQuery setVariables/reobserve with new variables reports partial data unexpectedly

[jerelmiller]

Issue Description

When using the core client.watchQuery() method which returns an ObservableQuery, changing variables to a result that has partial data will report that partial data even when returnPartialData is set to false.

This does not affect useQuery however because useQuery uses getCurrentResult() under the hood whenever a cache update occurs, which does not demonstrate this behavior.

We'd like our React hooks and core APIs to have the same behavior so that non-React users (and other frameworks) don't need to handle these differences.

Link to Reproduction

#11581

Reproduction Steps

No response

@apollo/client version

3.9.4