Fix cleanup-integration script to really delete buildpacks
Fix cleanup-integration script to really delete buildpacks

We recently changed this script to simplify the way we were deleting
buildpacks. We accidentally left off the part where we pipe the
delete-buildpack command into `bash`, so we were just printing these
commands out instead of really executing them. This fixes that!

Authored-by: Reid Mitchell <15b84f3bcf1e0a1a99817cc9360cedc980d7c5b6@pivotal.io>

cloudfoundry/cli,cloudfoundry/cli,cloudfoundry/cli