Sentry should have two different projects for swh-indexer and swh-indexer-storage

Currently, both are in the swh-indexer project, so Sentry doesn't understand that idx-storage and indexers can have different versions, and it causes it to mark some issues like https://sentry.softwareheritage.org/organizations/swh/issues/4062 as regressions.

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Migrated from T3015 (view on Phabricator)