The PR at #126150 introduced an integration test that looked at all combinations of left-vs-right types during LOOKUP JOIN and made assertions on whether they should succeed or fail. The review comments pointed out that instead of making many different lookup indices for each type, we could just have one main and one lookup index, each with fields for all types, and use RENAME to allow mixed-type testing.

This issue recommends making exactly that simplification. It should make the code easier to follow as well as improve test performance. Previously about half of the 20s the test took to run was likely index setup. This could be reduced quite a bit.