Solve fsGroup issue

* Respect recent api changes and Move most of securityContext to pod level,
  only readOnlyRootFilesystem is stayed on container one

* Solves
```
Error: UPGRADE FAILED: error validating "": error validating data: ValidationError(Deployment.spec.template.spec.containers[0].securityContext): unknown field "fsGroup" in io.k8s.api.core.v1.SecurityContext
```
on eks reference deployment

* Fixes #293

Signed-off-by: Yury Tsarev <yury.tsarev@absa.africa>

chart/k8gb/templates/external-dns/external-dns-ns1.yaml

@@ -15,6 +15,10 @@ spec:
         app: external-dns-ns1
     spec:
       serviceAccountName: external-dns
+      securityContext:
+        fsGroup: 65534 # For ExternalDNS to be able to read Kubernetes and AWS token files
+        runAsUser: 1000
+        runAsNonRoot: true
       containers:
       - name: external-dns
         image: {{ .Values.externaldns.image }}
@@ -41,8 +45,5 @@ spec:
             memory: "128Mi"
             cpu: "500m"
         securityContext:
-          runAsUser: 1000
-          runAsNonRoot: true
           readOnlyRootFilesystem: true
-          fsGroup: 65534 # For ExternalDNS to be able to read Kubernetes and AWS token files
 {{ end }}

chart/k8gb/templates/external-dns/external-dns-route53.yaml

@@ -15,6 +15,10 @@ spec:
         app: external-dns-route53
     spec:
       serviceAccountName: external-dns
+      securityContext:
+        fsGroup: 65534 # For ExternalDNS to be able to read Kubernetes and AWS token files
+        runAsUser: 1000
+        runAsNonRoot: true
       containers:
       - name: external-dns
         image: {{ .Values.externaldns.image }}
@@ -35,8 +39,5 @@ spec:
             memory: "128Mi"
             cpu: "500m"
         securityContext:
-          fsGroup: 65534 # For ExternalDNS to be able to read Kubernetes and AWS token files
-          runAsUser: 1000
-          runAsNonRoot: true
           readOnlyRootFilesystem: true
 {{ end }}