Add policy check if cross reference system notes are accessible

See merge request gitlab/gitlabhq!3425

Only render fixed number of mermaid blocks

See merge request gitlab/gitlabhq!3429

Filter not accessible label events

See merge request gitlab/gitlabhq!3439

Fix Gitaly SearchBlobs flag RPC injection [Gitaly v1.65.1]

See merge request gitlab/gitlabhq!3443

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Label events may use cross-project or cross-group references,
if the projects are not accessible by user, we don't show these
label events.

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