remove destroy persisters calls

[bogdan-rosianu]

Description of the reasoning behind the pull request (what feature was missing / how the problem was manifesting itself / what was the motive behind the refactoring)

• if a persister could have not been created (for example, when extra tweaking the configuration and the system's ulimit was too low), all the opened DBs would have been destroyed, which should only be valid if the databases are created (not opened)

Proposed Changes

• remove the code block that called DestroyUnit()

Testing procedure

• specific scenario already tested and validated
• these changes don't affect other storage operations

[gabi-vuls]

System test passed.