[MacPorts] #46301: postgrey: use add_users and notes

[MacPorts]

#46301: postgrey: use add_users and notes
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 Reporter:  ryandesign@…  |      Owner:  cbellot@…
     Type:  defect        |     Status:  new
 Priority:  Normal        |  Milestone:
Component:  ports         |    Version:
 Keywords:                |       Port:  postgrey
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 postgrey needs to use `add_users` and `notes` in the global part of the
 portfile instead of using `adduser` and `addgroup` in the destroot block
 and `ui_msg` in a post-install block.

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Ticket URL: <https://trac.macports.org/ticket/46301>
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