Lazy connections are now opt-out and controlled centrally by NB_LAZY_CONN,
MDM policy (lazyConnection), and the management feature flag (#6617). The
per-device UI toggle no longer fits this model: after #6617 the daemon stopped
persisting the setting and dropped it from GetConfig, so the Wails toggle always
read back OFF and its writes did not survive a restart.
Remove the toggle and the orphaned runtime plumbing, matching what main did for
the Fyne UI:
- drop the toggle from SettingsNetwork and the lazy i18n keys
- drop LazyConnectionEnabled from the UI settings service and SetConfig request
- drop the runtime-apply block in server.SetConfig
- delete Engine.SetLazyConnEnabled and ConnMgr.SetLocalLazyConn
The proto fields and FullStatus status reporting are left intact.
d594afff38