Change random property invalidation to full coverage

[robinmackaij]

Currently, the validation of 4xx codes randomly selects one of the properties that, when invalidated, will cause the desired error response. To improve the coverage and remove the possibility of flaky tests (due to a faulty property not being hit every test run), this should be changed.

Target implementation:

• loop over all properties, return generator with each invalidated data set
  • remove every required property
  • violate every constraint
  • invalid type for each property
• perform request for each invalidated data set and perform all validations

Question: fail test case on first fail or continue with remaining properties / invalidations?