HSD8-1577 | Remove D7 unused importers

[sethprime]

Summary

Adds an update hook to remove unused D7 content importers in hs_migrate, and removes their config files.

Importer status: https://docs.google.com/spreadsheets/d/1-mQg46wHXhqXQUPkzPXD_OFtSb8_OOq8NszVafL3LwA

Need Review By (Date)

Urgency

Low

Steps to Test

1. Pull changes.
2. Run the database update.
3. Verify that the importers are removed.

Review Tasks

Backend / Functional Validation

Code

• Are the naming conventions following our standards?
• Are PHP functions and variables in snake_case and not camelCase?
• Does Drupal code follow Drupal Coding Standards?
• Does the code have sufficient inline comments?
• Is there anything in this code that would be hidden or hard to discover through the UI?
• Are there any code smells?
• Are tests provided?

Code security

• Is all user input properly sanitized when rendered?
• Any obvious security flaws or new areas for attack?

General

• Is there anything included in this PR that is not related to the problem it is trying to solve?
• Is the approach to the problem appropriate?

[pookmish]

Just a couple small tweaks needed. Otherwise this is a good approach.

[pookmish]

LGTM. Thanks for the requested changes.