Changed the way of waiting for task completion.

[brdw87]

Pull Request summary:

Change the way of waiting for task completion. Now Task().wait_for_complete() waits for the end of task, not as in the previous implementation for the first fail

Description of changes:

The previous implementation stops pooling task object when at least one subtask has failed. It caused problems with further processing the next tasks, some of them depend on the still running task.

Checklist:

• Make sure to run pre-commit before committing changes
• Make sure all checks have passed
• PR description is clear and comprehensive
• Mentioned the issue that this PR solves (if applicable)
• Make sure you test the changes