Add assertions to OpenTelemetryFrontPagePerformanceTest::testFrontPageColdCache()

I am adding 📌 Add assertions to OpenTelemetryFrontPagePerformanceTest::testFrontPageColdCache() Active as a related issue since it affects the same test class as this issue. (These issues are already siblings, or children of the same meta issue).

MR 9596 adds the suggested assertions. It asserts the number of queries (104), but not the specific queries. Do we want that?

There are several failing tests for MR 9596, but the test I updated is not one of them.

Re-ran the failures and they're all green.

Giving it my best shot looking at the numbers and don't see any issue.

This looks great but per #6 it would be worth adding the number of queries here too (or opening a follow-up to do that) - helps catch the potential case where a query is removed but a different query is added.