Fixed: Canvas is busy

[bsekachev]

Motivation and context

Resolve #1922

How has this been tested?

Manual testing
@dvkruchinin Could you please write a test for the issue.
Scenario is:

1. Open a job (should contain at least two images)
2. Draw a shape on the first image
3. Draw a shape on the second image
4. Switch player back button mode to "back with a filter" (right click by the button and select)
5. Start resizing (or dragging) a shape on the second frame
6. Press the shortcut [D] to go to the first frame
7. CVAT goes to fail view before the fix and nothing happens after fix

Checklist

• I submit my changes into the develop branch
• I have added description of my changes into CHANGELOG file
• I have updated the documentation accordingly
• I have added tests to cover my changes
• I have linked related issues (read github docs)
• I have increased versions of npm packages if it is necessary (cvat-canvas,
  cvat-core, cvat-data and cvat-ui)

License

• I submit my code changes under the same MIT License that covers the project.
  Feel free to contact the maintainers if that's a concern.
• I have updated the license header for each file (see an example below)

# Copyright (C) 2020 Intel Corporation
#
# SPDX-License-Identifier: MIT

[coveralls]

Coverage increased (+0.02%) to 62.831% when pulling 4ef1de0 on bs/fixed_issue_1922 into f0d99ee on develop.

[dvkruchinin]

Sure. The test will be written.