feat: Use sharedInformer for watch

[helayoty]

Use SharedInformer and add a delete event instead of watch. This will keep the channel open.

[helayoty]

manual e2e:

...
NAME: carbon-e2e
LAST DEPLOYED: Mon Apr 10 08:35:36 2023
NAMESPACE: default
STATUS: deployed
REVISION: 1
TEST SUITE: None
+ kubectl wait --for=condition=available deploy carbon-e2e-carbon-intensity-exporter -n kube-system --timeout=300s
deployment.apps/carbon-e2e-carbon-intensity-exporter condition met
+ sleep 15
+ kubectl get configmap carbon-intensity -n kube-system
NAME               DATA   AGE
carbon-intensity   7      10s
+ kubectl describe configmap carbon-intensity -n kube-system
Name:         carbon-intensity
Namespace:    kube-system
Labels:       <none>
Annotations:  <none>

Data
====
forecastDateTime:
----
2023-04-10 15:40:00 +0000 UTC
lastHeartbeatTime:
----
2023-04-10 15:35:45.209475964 +0000 UTC m=+5.899156339
maxForecast:
----
579.523333
message:
----

minForecast:
----
463.519714
numOfRecords:
----
288

BinaryData
====
data: 29048 bytes

Events:  <none>
+ sleep 10
+ kubectl delete configmap carbon-intensity -n kube-system
configmap "carbon-intensity" deleted
+ sleep 15
+ kubectl get configmap carbon-intensity -n kube-system
NAME               DATA   AGE
carbon-intensity   7      5s
+ kubectl describe configmap carbon-intensity -n kube-system
Name:         carbon-intensity
Namespace:    kube-system
Labels:       <none>
Annotations:  <none>

Data
====
message:
----

minForecast:
----
463.519714
numOfRecords:
----
288
forecastDateTime:
----
2023-04-10 15:40:00 +0000 UTC
lastHeartbeatTime:
----
2023-04-10 15:36:15.448189018 +0000 UTC m=+36.137659444
maxForecast:
----
579.523333

BinaryData
====
data: 29048 bytes

Events:  <none>
+ sleep 5
+++ kubectl get pods -n kube-system -o=name
+++ grep carbon-e2e-carbon-intensity-exporter
+++ sed 's/^.\{4\}//'
++ echo carbon-e2e-carbon-intensity-exporter-778578866d-98tcx
+ kubectl logs carbon-e2e-carbon-intensity-exporter-778578866d-98tcx -c carbon-data-exporter -n kube-system
I0410 15:35:44.350814       1 options.go:108] Neither kubeconfig file nor control plane URL was specified. Falling back to in-cluster config.
I0410 15:35:45.215290       1 configmap.go:72] configMap carbon-intensity has been created
I0410 15:36:00.322859       1 configmap.go:94] configMap carbon-intensity has been deleted
I0410 15:36:00.467358       1 configmap.go:72] configMap carbon-intensity has been created
I0410 15:36:05.301274       1 configmap.go:72] configMap carbon-intensity has been created
I0410 15:36:15.328760       1 configmap.go:94] configMap carbon-intensity has been deleted
I0410 15:36:15.457186       1 configmap.go:72] configMap carbon-intensity has been created
+ cleanup
+ kind delete cluster -n carbon-e2e
Deleting cluster "carbon-e2e" ...
Deleted nodes: ["carbon-e2e-control-plane"]