#2053 - Stop Celery Chains on Expected Aborts

[k-macmillan]

Description

Evaluated chains and identified which chain tasks could raise non-technical exceptions. Prevented non-technical exceptions from being raised so the Celery task does not "fail" when it has hit an expected end such as a person has opted out. This is going to help us keep an eye on actual failures.

Created documentation to help understand expected vs unexpected celery task failures.

# noqa has been added to methods that exceeded complexity thresholds. Those extra if blocks (and the noqa) will be removed by the Feature Flag cleanup ticket.

issue #2053

How Has This Been Tested?

Unit tests and deployed with a regression test passing.

Checklist

• [x] I have assigned myself to this PR
• [x] PR has an appropriate title: #9999 - What the thing does
• [x] PR has a detailed description, including links to specific documentation
• [x] I have added the appropriate labels to the PR.
• [x] I did not remove any parts of the template, such as checkboxes even if they are not used
• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to any documentation
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works. Testing guidelines
• [x] I have ensured the latest main is merged into my branch and all checks are green prior to review
• [x] New and existing unit tests pass locally with my changes
• [ ] Any dependent changes have been merged and published in downstream modules
• [x] The ticket was moved into the DEV test column when I began testing this change