Enable toggling gnbsim deployment

Change-Id: Ic81eb6a363400446981b8ef02aadc5c6c381d58b
diff --git a/aether-2.0/sd-core-5g-values.yaml b/aether-2.0/sd-core-5g-values.yaml
index fae56ab..8753043 100644
--- a/aether-2.0/sd-core-5g-values.yaml
+++ b/aether-2.0/sd-core-5g-values.yaml
@@ -162,7 +162,7 @@
             hostname: "upf"
 
 5g-ran-sim:
-  enable: true
+  enable: ${ENABLE_GNBSIM}
   resources:
     enabled: false
   images: