Deprecate sync tags

Problem/Motivation

Piwik PRO is deprecating the old sync tags in favor of the async tags. This will happen in January 2025. More information about this change is available in https://help.piwik.pro/support/tag-manager/sunset-of-synchronous-contain....

At the moment there is a setting in the module that allows the administrator to enable the sync tag containers.

There is on going work to move the script code from PHP files to external JS files in task #3482342: Move JS snippets to separate script files. This change is not soon needed anymore so those files do not need updating at the moment.

Steps to reproduce

-

Proposed resolution

Because the sync tags are deprecated the script is not going to work later. We should remove the current module setting and remove the sync script from the code.

Remaining tasks

1. Remove module setting Additional container (sync).
2. Remove code from the module that the setting controls.
3. Update tests to reflect the change.

User interface changes

1. Admin setting for the sync tag container is removed.

API changes

1. No scripts are embedded for sync tags.

Data model changes

1. Config schema needs to be updated and the old configurations cleaned out.