Clean up onvif and autotracking (#24559)

* simplify onvif and autotracking code

Removes about 230 lines from the ONVIF controller and autotracker without changing how PTZ moves are calculated. `OnvifController` no longer keeps its own `camera_configs` copy of the camera config, the cached `GetStatus`, `GetServiceCapabilities`, and `AbsoluteMove` request objects are gone in favor of plain dicts at the call site, and `PtzAutoTrackerThread` is merged into `PtzAutoTracker`. Repeated blocks in the autotracker (waiting for the motor to stop, disabling autotracking on a failed setup step) are now single helpers.

* use camera config for autotracking enabled state

Camera processes read autotracking state from a shared `autotracker_enabled` value that the dispatcher and autotracker had to keep in sync with the config by hand. Camera processes now subscribe to the `autotracking` and `onvif` config updates and read `onvif.autotracking.enabled` directly, so the shared value and the autotracker's mirroring method are gone. `_disable` now publishes its change so the camera process hears about it. Also removes `tracking_active`, which was set and cleared but never read.

* compute max target box from live zoom factor

* fix autotracking debug overlay max target box lookup

* make max target box a function of zoom factor

frigate/comms/dispatcher.py

@@ -759,15 +759,13 @@ class Dispatcher:
                     "Autotracking must be enabled in the config to be turned on via MQTT."
                 )
                 return
-            if not self.ptz_metrics[camera_name].autotracker_enabled.value:
+            if not ptz_autotracker_settings.enabled:
                 logger.info(f"Turning on ptz autotracker for {camera_name}")
-                self.ptz_metrics[camera_name].autotracker_enabled.value = True
                 self.ptz_metrics[camera_name].start_time.value = 0
                 ptz_autotracker_settings.enabled = True
         elif payload == "OFF":
-            if self.ptz_metrics[camera_name].autotracker_enabled.value:
+            if ptz_autotracker_settings.enabled:
                 logger.info(f"Turning off ptz autotracker for {camera_name}")
-                self.ptz_metrics[camera_name].autotracker_enabled.value = False
                 self.ptz_metrics[camera_name].start_time.value = 0
                 ptz_autotracker_settings.enabled = False