Walrus bucket_tests.py and object_tests.py updates for better S3 coverage

Converted the testcases/cloud_user/walrus/walrus_bucket.py and testcases/cloud_user/walrus/walrus_object.py test suites into testcases/cloud_user/s3/bucket_tests.py and object_tests.py respectively so they execute in the eutester framework.

Not all tests pass. Some fail due to test errors and others due to Walrus bugs, haven't had the time to explore each case. But, the suites run, so we can incrementally fix them later.