cleanup: removes uneeded annotation when not using network policy (#1884)

#### What type of PR is this?

<!--
Add one of the following kinds:
/kind bug
/kind documentation
/kind feature
-->

/kind cleanup

#### What this PR does / why we need it:

Removes the network policy annotation which is not needed (we are not
generating network policy)

#### Which issue(s) this PR fixes:
<!--
*Automatically closes linked issue when PR is merged.
Usage: `Fixes #<issue number>`, or `Fixes (paste link of issue)`.
-->
Fixes https://github.com/kubernetes/kompose/issues/1759

#### Special notes for your reviewer:

script/test/fixtures/configmap-volume/output-k8s-withlabel.yaml

@@ -15,7 +15,6 @@ spec:
   template:
     metadata:
       labels:
-        io.kompose.network/configmap-volume-default: "true"
         io.kompose.service: db
     spec:
       containers:
@@ -63,7 +62,6 @@ spec:
   template:
     metadata:
       labels:
-        io.kompose.network/configmap-volume-default: "true"
         io.kompose.service: web
     spec:
       containers:

script/test/fixtures/configmap-volume/output-k8s.yaml

@@ -15,7 +15,6 @@ spec:
   template:
     metadata:
       labels:
-        io.kompose.network/configmap-volume-default: "true"
         io.kompose.service: db
     spec:
       containers:
@@ -64,7 +63,6 @@ spec:
   template:
     metadata:
       labels:
-        io.kompose.network/configmap-volume-default: "true"
         io.kompose.service: web
     spec:
       containers:

script/test/fixtures/configmap-volume/output-os-withlabel.yaml

@@ -14,7 +14,6 @@ spec:
   template:
     metadata:
       labels:
-        io.kompose.network/configmap-volume-default: "true"
         io.kompose.service: db
     spec:
       containers:
@@ -90,7 +89,6 @@ spec:
   template:
     metadata:
       labels:
-        io.kompose.network/configmap-volume-default: "true"
         io.kompose.service: web
     spec:
       containers:

script/test/fixtures/configmap-volume/output-os.yaml

@@ -14,7 +14,6 @@ spec:
   template:
     metadata:
       labels:
-        io.kompose.network/configmap-volume-default: "true"
         io.kompose.service: db
     spec:
       containers:
@@ -91,7 +90,6 @@ spec:
   template:
     metadata:
       labels:
-        io.kompose.network/configmap-volume-default: "true"
         io.kompose.service: web
     spec:
       containers: