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

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

charts/kube-aws/ebs-loss-by-tag/engine.yaml

@@ -26,3 +26,7 @@ spec:
             # provide the region name of the instance
             - name: REGION
               value: ''
+
+            - name: VOLUME_AFFECTED_PERC
+              value: '' 
+                   

charts/kube-aws/ec2-terminate-by-tag/engine.yaml

@@ -31,3 +31,7 @@ spec:
             # enable it if the target instance is a part of self-managed nodegroup.
             - name: MANAGED_NODEGROUP
               value: 'disable'
+            
+             # Target the percentage of instance filtered from tag
+            - name: INSTANCE_AFFECTED_PERC
+              value: ''