Use test_case/default instead of the directory named with a pod's name.

Use test_case/default instead of the directory named with a pod's name.

1. For qtip ci job, use test_cases/default for all pods.
2. It needn't to specify ip in test case files.
3. Remove customized configurations in test case files.

Change-Id: I4fb6210c024aacc4d1ed915939c0aabcfa60bb57
Signed-off-by: wu.zhihui <wu.zhihui1@zte.com.cn>