main: Shut down prometheus with verbose_shutdown()
main: Shut down prometheus with verbose_shutdown()

Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>

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v2:
- Have stop easrlier so that exception in start/listen do
  not prevent prometheu.stop from calling

avikivity/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla