[meta] Tasks to deprecate Statistics

Problem/Motivation

Track the steps needed to remove extension Statistics from core to contrib. See Remove a core module and move it to a contributed project of the deprecation policy.

The removal of extension Statistics was approved in #3266457: [Policy] Deprecate Statistics module in D10 and move to contrib in D11

Remaining tasks

1. Done. Begin finding someone to maintain the contrib version of the extension. @fgm has agreed to maintain the contrib project.
2. Done Move integrations implemented by other modules to the extension.
   Create child issues or child meta issues, as needed, to address the following points. Not all points will apply to all extensions.
   • Move non-migration tests to the extension. #3341098: Move non-migrations tests to Statistics
   • Move Help Topics to the extension. #3341019: Move help topics to statistics module
   • Remove the extension from one or more profiles. Statistics is not used is any core profiles.
   • Remove templates from the extension’s markup. Statistics does not have templates.
   • For a module, handle migrations, if the module has migrations.
     1. Copy the drupal 6 and drupal 7 test fixtures to the module so they remain independent of any core changes to the fixture.
     2. Migration yml and processes that are in the module move with the module to contrib.
     3. Move migration tests to the module. #3341053: Move migration tests to the Statistics module
     4. Keep all the assertions in core tests related to module as much as possible.
     5. Migration yml and processes that are outside the module but support the upgrade path for that module stay in core.
     6. The functional tests in migrate_drupal_ui will need to change.
     7. The drupal 6 and drupal 7 test fixtures stay the same.
3. Done Do a thorough search of core for any remaining references to the extension. If references are found, outside of the extension, then create issues to remove the references.
   #3410210: Remove statistics module from comments
4. Create the contrib project with a stable release. Follow the process in Create the contrib project with a stable release for creating the sub tree split.
5. Deprecate the core extension. #3413917: Deprecate the Statistics module.