Add generic test coverage around Entity List Builders

Retitling. There should be generic test coverage around entity list builders implemented in Core to verify they're using the defined methods properly. Although I feel like this could be a PHPStan rule versus explicit test. "You didn't call the query method when loading entities" like the issue which spawned this.

I'm not sure that we should do anything in core for this. The issue that spawned this problem is not something we'd write a test for and I also doubt the value of a PHPStan rule.