compliance_markup::enforcement set to a string causes major performance issues

If you incorrectly set compliance_markup::enforcement to the string disa_stig instead of the array ['disa_stig'], catalog compilation times spike to a ridiculous level.

In this case, we should either warn and do nothing, or we should assume that the user meant to pass an array of that single string and behave the same as if an array was passed.

This is the root cause of SIMP-8122.