Tweak Package Cleaner
Tweak Package Cleaner

Make it delete only outputDir/gcsPrefix, so it doesn't delete
index_generator's stuff. Otherwise, index_generator may not expect this
and raise errors.

astashov/dartdocorg,astashov/dartdocorg,astashov/dartdocs.org,astashov/dartdoc-generator,astashov/dartdocs.org,astashov/dartdocorg,astashov/dartdoc-generator,astashov/dartdoc-generator,astashov/dartdocs.org