chore(env): Adding required env inside chaosengine (#479)

Signed-off-by: shubhamchaudhary <shubham@chaosnative.com>

charts/generic/pod-network-duplication/engine.yaml

@@ -21,10 +21,6 @@ spec:
             - name: TOTAL_CHAOS_DURATION
               value: '60' # in seconds
 
-            #Network interface inside target container
-            - name: NETWORK_INTERFACE
-              value: 'eth0'    
-
             - name: NETWORK_PACKET_DUPLICATION_PERCENTAGE
               value: '100'
   
@@ -37,3 +33,7 @@ spec:
             # provide the socket file path
             - name: SOCKET_PATH
               value: '/var/run/docker.sock'
+              
+            ## percentage of total pods to target
+            - name: PODS_AFFECTED_PERC
+              value: ''