* restructure tests
restructure TestValidateStatefulSet and TestValidateStatefulSetUpdate to be an array and accept list of expected errors. in this commits, no tests were changed and expected errors are not filled yet
* add expected errors
adding expected errors and making the tests pass, without making any changes to the tests
* clean up TestValidateStatefulSet error cases
* clean up TestValidateStatefulSetUpdate cases
* validate new statefulset as part of update validation
* address PR comments