Inconsistent permissions for accessing private snippets
### Problem Snippets explore feature (https://gitlab.com/explore/snippets) allows admin and auditor role to see private snippets of other users. However, the Snippet API list endpoint (`api/v4/snippets`) is restricted to show only personal or public snippets for admin and auditors. But it works for private snippets if we request them directly by id (`api/v4/snippets/25`). ### Proposal * Match the behavior between the GitLab UI and the API functionality. * Update the documentation Related issues: * https://gitlab.com/gitlab-org/gitlab/-/issues/212729+ * https://gitlab.com/gitlab-org/gitlab/-/issues/209005+
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