Verify LTS interface implementation against test LTS share

[phwissmann]

In order to make sure the LTS mock implements the same interface and behavior as the LTS, tests should be run against an LTS test share

• [ ] get access LTS test share (probably needs to DNS to whitelist access, can therefore only be run on openem-dev.ethz.ch)
• [ ] execute archive/retrieve test
• [ ] fix LTS mock if behavior is different