feat(1765): update tests, move unit test to proper file, improve removeEmptyInterfaces algo

Signed-off-by: Martin Jirku <martin@jirku.sk>

script/test/fixtures/compose-env-interpolation/output-k8s.yaml

@@ -2,7 +2,6 @@
 apiVersion: v1
 kind: Service
 metadata:
-  creationTimestamp: null
   labels:
     io.kompose.service: foo
   name: foo
@@ -18,7 +17,6 @@ spec:
 apiVersion: apps/v1
 kind: Deployment
 metadata:
-  creationTimestamp: null
   labels:
     io.kompose.service: foo
   name: foo
@@ -27,10 +25,8 @@ spec:
   selector:
     matchLabels:
       io.kompose.service: foo
-  strategy: {}
   template:
     metadata:
-      creationTimestamp: null
       labels:
         io.kompose.network/compose-env-interpolation-default: "true"
         io.kompose.service: foo
@@ -43,6 +39,5 @@ spec:
             - containerPort: 80
               hostPort: 80
               protocol: TCP
-          resources: {}
       restartPolicy: Always