landscape: defer removing metadata until on-leave thread
Addresses graphs not being archived correctly, and causing spurious
notifications
;< ~ bind:m (raw-poke-our %metadata-pull-hook pull-hook-act)
;< ~ bind:m (raw-poke-our %group-pull-hook pull-hook-act)
;< ~ bind:m (raw-poke-our %group-store %group-update-0 !>([%remove-group rid ~]))
-;< ~ bind:m (cleanup-md:view rid)
(pure:m !>(~))
