%18.8 Backport of 'Fix re-archiving projects and subgroups after group unarchive'

What does this MR do and why?

When a group was unarchived, the unarchive_descendants! and unarchive_all_projects! methods only updated namespace_settings.archived and projects.archived columns but did not reset the namespaces.state column. This left the state machine in an archived state, preventing projects and subgroups from being re-archived later. Update both methods to also reset namespaces.state to ancestor_inherited for previously archived descendants and project namespaces.

Backporting because it's a severity2 bug Fix re-archiving projects and subgroups after g... (!225641 - merged).

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