Two Moonraker user presets on different ports (:7125, :7126) share the
same printer agent type. switch_printer_agent() only called select_machine()
when the agent *type* changed — not when the host changed within the same
agent. A user→user preset switch therefore left the MachineObject pointing
at the first connected printer, causing AMS sync to always query the wrong
host.
Fix: when the agent type stays the same (and is not the BBL agent),
also call select_machine() so the host is re-resolved from the current
preset and set_selected_machine() reconnects to the correct Moonraker
instance.
Fixes: AMS Sync locked to first printer in multi-printer sessions (SirPeroples)
87f6e62f26