Fix transient clusters termination

The problem started to appear in our CI jobs on March 26.
See the bug description for details.

Closes-Bug: #1298391

Change-Id: I4b4102f12efd27be13255e7b0ca120d66a078673
Fix parallel running integration tests with vanilla plugins

Closes bug: #1298441

Change-Id: I7820ae0bfac8f911cafc69a3ce2e57daf09f6196
Merge "Fix transient clusters termination"
Merge "Fix parallel running integration tests with vanilla plugins"