Update/Fix flaky tests

[AliyanH]

We can either deal with flaky tests using playwright - https://playwright.dev/docs/test-retries#retries

or try to pinpoint all known flaky tests and fix them:

• layers/multipleHeterogeneousQueryExtents.test.js:75:3 › Multiple Extent Queries with heterogeneous response content types › Enusre extents that are unchecked or removed are not included in query results