config: disable heuristic gap-fill apps in hybrid mode demos

Manifest defines all apps - gap-fill apps from runtime discovery
(e.g., _param_client_node orphan) are noise. Set allow_heuristic_apps
to false in all 3 demo configs.

Note: create_synthetic_areas workaround removed - the root-namespace
area bug was fixed upstream (ros2_medkit cffce4e1).

Author: bburda

demos/moveit_pick_place/config/medkit_params.yaml

@@ -25,6 +25,9 @@ diagnostics:
         manifest_strict_validation: true
         runtime:
           create_synthetic_components: false  # Manifest defines components
+        merge_pipeline:
+          gap_fill:
+            allow_heuristic_apps: false  # Manifest defines all apps
 
       # Plugin configuration (set by launch file when .so paths are resolved)
       plugins: [""]

demos/sensor_diagnostics/config/medkit_params.yaml

@@ -23,6 +23,9 @@ diagnostics:
         manifest_strict_validation: true
         runtime:
           create_synthetic_components: false  # Manifest defines components
+        merge_pipeline:
+          gap_fill:
+            allow_heuristic_apps: false  # Manifest defines all apps
 
       # Plugin configuration (set by launch file when .so paths are resolved)
       plugins: [""]

demos/turtlebot3_integration/config/medkit_params.yaml

@@ -24,6 +24,9 @@ diagnostics:
         manifest_strict_validation: true
         runtime:
           create_synthetic_components: false  # Manifest defines components
+        merge_pipeline:
+          gap_fill:
+            allow_heuristic_apps: false  # Manifest defines all apps
 
       # Plugin configuration (set by launch file when .so paths are resolved)
       plugins: [""]