- The namespace of the JITM class in the jetpack-jitm package was changed in v1.6.
  Check for both namespaces in the Config package.

- Add a new parameter, $log_notice, to the ensure_class method. The default value
  of this parameter should be true. This parameter allows the calling function to
  choose whether the notice should be generated when the class is not found.

Committed via a GitHub action: https://github.com/automattic/jetpack/runs/148393380