Large number of CRITICAL errors in cta-taped - "In BackendPopulator::~BackendPopulator(): error deleting agent (cta::exception::Exception). Backtrace follows."

Relates to this issue: https://gitlab.cern.ch/cta/operations/-/issues/1020

Steps to understand the error:

• Reproduce the error
  • Add unit test: Test two retrieve requests instead of one(example of a test with one can be found here)