Fix adjoint for ChangeOfVariables

[lxvm]

Checklist

• Appropriate tests were added
• Any code changes were done in a way that does not break public API
• All documentation related to code changes were updated
• The new code follows the
  contributor guidelines, in particular the SciML Style Guide and
  COLPRAC.
• Any new documentation only uses public API

Additional context

The derivative tests did not catch that the ChangeOfVariables adjoint was incorrect because they all used lb, ub = 1, 3 for which the scaling factor (ub - lb) / 2 = 1. So, I added another test with a non-trivial scaling factor as well as an affine change of variables.