The inter-query cache has intermittent test failures

[johanfylling]

The tests for the inter-query cache in topdown/cache/cache_test.go has intermittent, failing tests.

E.g.: https://github.com/open-policy-agent/opa/actions/runs/10618059480/job/29432842474?pr=6977#step:6:175

This could be indicative of an issue in the cache itself; or it could be a timing issue localized to the tests, as these seem to heavily rely on time.Sleep().

[stale]

This issue has been automatically marked as inactive because it has not had any activity in the last 30 days. Although currently inactive, the issue could still be considered and actively worked on in the future. More details about the use-case this issue attempts to address, the value provided by completing it or possible solutions to resolve it would help to prioritize the issue.