Integration test suite for query range

[srikanthccv]

Query processing in our system relies heavily on the query_range endpoint and querier interface, which are central to key features like dashboards, alerting, and explorer pages. The complexity of our system - including diverse panel types, query types, panel options, data sources with varied caching strategies, and multiple querier versions - makes comprehensive manual testing impractical for every significant update. To confidently deploy changes, we need a integration test suite specifically designed for the query_range endpoint and querier components