Chore(appengine) Remove deprecated samples#13833

XrossFox wants to merge 2 commits intoGoogleCloudPlatform:mainGoogleCloudPlatform/python-docs-samples:mainfrom

XrossFox:delete-python-3.7-and-earlier-dirXrossFox/python-docs-samples:delete-python-3.7-and-earlier-dirCopy head branch name to clipboard