#2011 - Notification status and status_reason consistency

[kalbfled]

Description

These changes ensure that a notification's "status reason" is always the empty string when the status is "delivered."

The underlying ticket cited a problem without an explicit way to reproduce it, so I went looking for problems. These changes cover all code paths as far as I can tell without a specific problem to fix.

issue #2011

How Has This Been Tested?

This is not easy to test because I don't know how to force providers to return a particular status. I'm relying heavily on unit tests.

• [x] new and modified unit tests pass
• [x] Send myself a text message, reply with STOP, and see that the status reason of the delivered message isn't overwritten with the "opted-out" blurb. See the full documentation of my testing here.

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
• [ ] 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