FCV variable on js tests are provided by the mongo shell, thus in 6.0 branch the ltestFCV will be 6.0.

configure_collection_balancing_setFCV.js tries to set the latestFCV.

So when this test run on the multiversion suite in the 6.0 branch it will try to set a 6.0 FCV on a 5.3 binary.

The solution would be to add the multiversion_incompatible tag to the test