Disable execution of tests for Akonadi on Windows.

Despite repeated manual kicks to clear stuck akonadiserver/akonadi_knut_resource/akonadi_control processes, it has failed to progress itself and is just tying up a builder.
Status Job ID Name Coverage
  Build
manual #3614
docker allowed to fail manual
kdeorg/appimage-base
manual #3615
docker allowed to fail manual
kdeorg/staticweb