[OpenCollective] update opencollective to api v2 (#9346)

* update opencollective to api v2

* fix tests

* fix: do not filter by accountType for opencollective/all

* remove 404

* remove required in schema

* cnt -> count

* keep by-tier code as-is

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Co-authored-by: repo-ranger[bot] <39074581+repo-ranger[bot]@users.noreply.github.com>