Data not cleaned up properly after s3 real storage tests

[phoebusm]

https://github.com/man-group/ArcticDB/blob/c0a350e3ba8149f4ec08d3297b983dfd65b2d560/python/tests/util/storage_test.py#L172

It assumes all libraries created by the S3 real storage tests have name starts with "test_", which is wrong in some cases, e.g.: https://github.com/man-group/ArcticDB/blob/c0a350e3ba8149f4ec08d3297b983dfd65b2d560/python/tests/integration/arcticdb/test_arctic_library_management.py#L400