fix: health check waits for tasks to finish before becoming unhealthy

[aneojgurhem]

Motivation

Avoid stopping compute plane due to unhealthy health check when tasks are being executed.

Description

Pollster health check has been changed to become unhealthy when there is no tasks in processing in the pollster. Shut down while not be triggered when health check becomes unhealthy, allowing the current tasks to continue. However, no new tasks will be taken from the queue storage. If the tasks does not access the storages during the time they are not available, it will not have any impact on the tasks. If a storage is missing at this point, the tasks should be set to error.

Testing

Unit tests were added. Unit tests and integration tests are passing.

Impact

No impact on infrastructure. If there are connection loss during the execution of the task and the connection comes back before the end of the task, the task should succeed.

Checklist

• My code adheres to the coding and style guidelines of the project.
• I have performed a self-review of my code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• I have thoroughly tested my modifications and added tests when necessary.
• Tests pass locally and in the CI.
• I have assessed the performance impact of my modifications.