This commit stops new users from installing Taxcloud. Taxcloud will keep working for customers who already had it installed in a previous version. Our Taxcloud modules will be released under LGPL, giving everyone the opportunity to migrate and maintain these modules for future versions if they have a need.

This commit follows a similar approach to
odoo/odoo@c9072dfe798d658246ca6fc255f95eb884a6d389. Using the installable flag in the manifest was considered but doesn't have the desired result:

- module installation doesn't error, instead it remains in the “to install” state
  - this leads to errors when loading the registry [1],
  - this prevents crons from running

The current approach still allows command-line manipulation which is needed for migration and allows us to keep the modules installed on runbot for support.

Dependencies of account_taxcloud don't get this hook, this allows existing customers to still install the right bridge module if needed. If account_taxcloud is not installed, then installing a dependency of it errors as expected.

An upgrade script isn't needed because upgrading any module will automatically sync the auto_install field from the manifests via ir.module.module's update_list().

[1] Some modules have inconsistent states, some dependencies may be
missing: ['account_taxcloud']

task-3516826