Fixed negative containers test for duplicate secret

The test_create_container_w_duplicate_secret_refs test is expected
to fail with an http 400.  Had to remove code which checked for a
successful return code (201) then use the container create return
code to assert the correct http 400 return code.  Also moved the
skip_on_issue call to the skip_open_issue decorator.

Change-Id: I0c9aad5f1aeda4c111f3fe0552a28a3da6660b48
Merge "Fixed negative containers test for duplicate secret"