modelrevert: boot fixes + strip remaining variable-rate cruft

controlsd:
- stop writing the removed 'no_lat_lane_change' persistent param
  (key isn't in the whitelist anymore). Write to
  frogpilot_variables.no_lat_lane_change instead so the carcontroller
  read still works and the lane-change-disengage feature is preserved.
- initialize self.driving_gear = False in __init__; it's set at the
  end of step() in update_frogpilot_variables but clearpilot_state_control
  reads it on the first iteration before that's run.

modeld:
- remove the remaining CLEARPILOT variable-rate / standby code path
  that was baked into the initial-import commit (the one our first
  commit captured). Constant 20fps, no ModelStandby/ModelStandbyTs
  writes, no params_memory reads for 'no_lat_lane_change' (which
  isn't registered anymore).
- drop now-unused locals (model_standby, last_standby_ts_write,
  params_memory).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

selfdrive/controls/controlsd.py

@@ -85,6 +85,7 @@ class Controls:
     self.speed_state = SpeedState()
     self.speed_state_frame = 0
     self.was_driving_gear = False
+    self.driving_gear = False
 
     self.radarless_model = self.params.get("Model", encoding='utf-8') in RADARLESS_MODELS
 
@@ -700,9 +701,9 @@ class Controls:
 
     if model_v2.meta.laneChangeState == LaneChangeState.laneChangeStarting and clearpilot_disable_lat_on_lane_change:
       CC.latActive = False
-      self.params_memory.put_bool("no_lat_lane_change", True)
+      self.frogpilot_variables.no_lat_lane_change = True
     else:
-      self.params_memory.put_bool("no_lat_lane_change", False)
+      self.frogpilot_variables.no_lat_lane_change = False
 
     if CS.leftBlinker or CS.rightBlinker:
       self.last_blinker_frame = self.sm.frame