[Gameplay] Remove TerritoryDecay from Roman Army Camp and Siege Walls

The territory decay of these structures didn't make much sense (gameplay
wise) and made those structures a pain to use.

Patch by: @wowgetoffyourcellphone
Accepted by: @real_tabasco_sauce
Differential Revision: https://code.wildfiregames.com/D5215
This was SVN commit r27978.

binaries/data/mods/public/simulation/templates/structures/rome/army_camp.xml

@@ -103,9 +103,7 @@
       <attack_impact_ranged>attack/impact/arrow_impact.xml</attack_impact_ranged>
     </SoundGroups>
   </Sound>
-  <TerritoryDecay>
+  <TerritoryDecay disable=""/>
-    <DecayRate op="mul">2</DecayRate>
-  </TerritoryDecay>
   <Trainer>
     <BatchTimeModifier>0.7</BatchTimeModifier>
     <Entities datatype="tokens">

binaries/data/mods/public/simulation/templates/structures/rome/siege_wall_gate.xml

@@ -45,6 +45,7 @@
   <StatusBars>
     <HeightOffset>13.5</HeightOffset>
   </StatusBars>
+  <TerritoryDecay disable=""/>
   <TerritoryInfluence disable=""/>
   <TurretHolder>
     <TurretPoints>

binaries/data/mods/public/simulation/templates/structures/rome/siege_wall_long.xml

@@ -42,6 +42,7 @@
   <StatusBars>
     <HeightOffset>7.7</HeightOffset>
   </StatusBars>
+  <TerritoryDecay disable=""/>
   <TerritoryInfluence disable=""/>
   <TurretHolder>
     <TurretPoints>

binaries/data/mods/public/simulation/templates/structures/rome/siege_wall_medium.xml

@@ -42,6 +42,7 @@
   <StatusBars>
     <HeightOffset>7.7</HeightOffset>
   </StatusBars>
+  <TerritoryDecay disable=""/>
   <TerritoryInfluence disable=""/>
   <TurretHolder>
     <TurretPoints>

binaries/data/mods/public/simulation/templates/structures/rome/siege_wall_short.xml

@@ -42,6 +42,7 @@
   <StatusBars>
     <HeightOffset>7.7</HeightOffset>
   </StatusBars>
+  <TerritoryDecay disable=""/>
   <TerritoryInfluence disable=""/>
   <VisualActor>
     <Actor>structures/romans/siege_wall_short.xml</Actor>

binaries/data/mods/public/simulation/templates/structures/rome/siege_wall_tower.xml

@@ -46,6 +46,7 @@
   <StatusBars>
     <HeightOffset>13.5</HeightOffset>
   </StatusBars>
+  <TerritoryDecay disable=""/>
   <TerritoryInfluence disable=""/>
   <TurretHolder>
     <TurretPoints>