ensure that mixed mode tests cover all scenarios provably #3604
Description
We had a case where the pull request validation ran fine (that does limited mixed mode testing) while the release build failed with an uplevel/downlevel incompatibility. That should not have happened. The query that caused the problem should not have worked even in the PR validation given that the PR should validate mixed mode tests that had compiled the query on a down level client.
Similarly, but on the other side of the spectrum, the mixed mode testing fails both tests:
JDBC In-Process then 4.5.10.0 and 4.5.10.0 then JDBC In-Process. I think only one should fail and the other should pass in this case as the query is clearly supported in the current version.
Can we make sure that these tests provably cover both cases, i.e. have the current version compile and have the other version compile in the other test?