Cover the rewrite shapes the middleware handles end-to-end against a
real OpenCloud server: root-anchored, item-anchored, deep paths,
trailing colon, and the "/<path>:/<suffix>" sub-route form. Also
assert that NOT_FOUND and PERMISSION_DENIED both collapse to 404.
The /permissions sub-route is registered only at /v1beta1, and the
v1beta1 GetDriveItem handler is share-jail-only, so the v1beta1
mount of the middleware is exercised through the permissions
scenario, since there is no other v1beta1 endpoint that works for
regular personal-drive items.
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