kaniko_build_args to reflect env in tests. Add prepare args test for test_fail...
kaniko_build_args to reflect env in tests. Add prepare args test for test_fail environment. Add kaniko build test for test_fail environment. Maove external registry build asserts job to .pre stage; asserts job exit code to reflect which tests failed. MR build default rule simplify. Prepare extra args default rules simplify. Prepare extra args parse input into a variable.