Pubdev: Do not rely on intrinsic metadata

The loader get enough information from extrinsic metadata to build a release object, checking intrinsic metadata was more error prone than useful.

It should fix some Sentry reported errors.

Remove 'information' and adapt release message

Adapt loader specifications documentation

Related T4465, #4530, #4583

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Migrated from D8640 (view on Phabricator)