[pudbev lister] use alternative packages list endpoint

Feedback from public review :

pub.dev community suggests to use https://pub.dev/api/package-names instead of https://pub.dev/api/packages (unofficial, will be deprecated soon)

see https://github.com/dart-lang/pub-dev/issues/6111#issuecomment-1293392619 for more info

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Migrated from T4665 (view on Phabricator)