Performance regression on canceling auto-annotation update task

Release candidate build version 33: Windows 64 bit (NSIS, full package)

Scenario:

1. Load "_common_data/fasta/Mycobacterium.fna".
2. Open "Find restriction site" dialog.
3. Click "Select All" button and save settings.
4. In Task section select "Auto-annotation update" task
5. Select Cancel operation from context menu
   Expected result: Cancel operation should finished in 30-40 sec
   as it was it UGENE version 1.29, 1.30, 1.31
   Current result: Cancel have finished after 8 min!
   Regression appeared since January 2019.

Affected test:
GUITest_regression_scenarios_test_3519_2