Remove obsolete tag from sdf

Signed-off-by: Nikodem Janik <nikodemj@gmail.com>

Author: nikodemj9

examples/worlds/gpu_lidar_sensor.sdf

@@ -162,7 +162,6 @@
               <resolution>0.01</resolution>
             </range>
           </lidar>
-          <alwaysOn>1</alwaysOn>
           <visualize>true</visualize>
         </sensor>
       </link>

examples/worlds/logical_camera_sensor.sdf

@@ -138,7 +138,6 @@
             <horizontal_fov>1.04719755</horizontal_fov>
             <aspect_ratio>1.778</aspect_ratio>
           </logical_camera>
-          <alwaysOn>1</alwaysOn>
           <visualize>true</visualize>
           <topic>logical_camera</topic>
           <enable_metrics>true</enable_metrics>

examples/worlds/visualize_frustum.sdf

@@ -433,7 +433,6 @@
             <horizontal_fov>1.04719755</horizontal_fov>
             <aspect_ratio>1.778</aspect_ratio>
           </logical_camera>
-          <alwaysOn>1</alwaysOn>
           <visualize>true</visualize>
           <topic>logical_camera</topic>
           <enable_metrics>true</enable_metrics>

test/worlds/gpu_lidar_sensor.sdf

@@ -146,7 +146,6 @@
               <resolution>0.01</resolution>
             </range>
           </ray>
-          <alwaysOn>1</alwaysOn>
           <visualize>true</visualize>
         </sensor>
       </link>

test/worlds/logical_camera_sensor.sdf

@@ -124,7 +124,6 @@
             <horizontal_fov>1.04719755</horizontal_fov>
             <aspect_ratio>1.778</aspect_ratio>
           </logical_camera>
-          <alwaysOn>1</alwaysOn>
           <visualize>true</visualize>
         </sensor>
       </link>
@@ -156,7 +155,6 @@
             <horizontal_fov>1.04719755</horizontal_fov>
             <aspect_ratio>1.778</aspect_ratio>
           </logical_camera>
-          <alwaysOn>1</alwaysOn>
           <visualize>true</visualize>
         </sensor>
       </link>