land_detector: move to same WQ as estimator

 - the primary data sources of the land detector run from the same WQ so
don't lose anything by serializing these modules

src/modules/land_detector/LandDetector.cpp

@@ -55,7 +55,7 @@ namespace land_detector
 
 LandDetector::LandDetector() :
 	ModuleParams(nullptr),
-	ScheduledWorkItem(MODULE_NAME, px4::wq_configurations::hp_default)
+	ScheduledWorkItem(MODULE_NAME, px4::wq_configurations::att_pos_ctrl)
 {
 	_land_detected.timestamp = hrt_absolute_time();
 	_land_detected.freefall = false;