please remove images for Apprenda in azure-quickstart-templates

Please remove the templates for https://github.com/Azure/azure-quickstart-templates/tree/master/apprenda60-express and
https://github.com/Azure/azure-quickstart-templates/tree/master/apprenda60-small

Apprenda no longer supports these images on azure and we should remove them from github.
We have removed our Azure marketplace offering for Apprenda some time ago.

Inspect the apprenda60-express and apprenda60-small template directories identified in the issue. Remove both obsolete templates, then verify that the repository no longer contains either Apprenda template; the issue is complete when both paths have been removed.

Written by the indexing model from the issue text.