Cancel the pending notify timeout when stopping a query

[hollandThomas]

The original stop method does not clear the pending notifyTimeout. When a query is stopped in the same tick and right after a cache update sets the notifyTimeout, the query is not removed correctly, as the notifyTimeout callback will recreate the QueryInfo. This might lead to undesired behavior, as queries are executed that should have been stopped already.

I could not find a suitable test to extend / was unsure how to add a new test for this.

Might be related to #6888

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

[apollo-cla]

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[benjamn]

Makes sense; thanks @hollandThomas!