remove stubbed decorator from tests of test_health.py

[Jameer Pathan]

Remove stubbed decorator for following tests because the checks which are used in tests are now available in foreman-maintain v0.4.3

• test_positive_check_upstream_repository
• test_positive_puppet_check_no_empty_cert_requests
• test_positive_puppet_check_empty_cert_requests

Also fix test_positive_foreman_maintain_health_check failing because of check puppet-check-no-empty-cert-requests which needs users permission. Fix the test by using --assumeyes option

[Jameer Pathan]

fixed in #85