Support loadbalancer interface between master and API LB (#796)

* Support loadbalancer interface between master and API LB

Simplify the relations between the master, worker, and API LB charms in
favor of the newer `loadbalancer` interface relation.

Part of [lp:1897818][]
Depends on:
  * juju-solutions/loadbalancer-interface#13
  * juju-solutions/interface-kube-control#33
  * charmed-kubernetes/charm-kubernetes-control-plane#153
  * charmed-kubernetes/charm-kubernetes-worker#84
  * charmed-kubernetes/charm-kubeapi-load-balancer#11

[lp:1897818]: https://bugs.launchpad.net/charmed-kubernetes-testing/+bug/1897818

* Split k8s-master:lb-provider relation into external / internal

* Update core and converged bundle fragments

fragments/k8s/cdk-converged/bundle.yaml

@@ -91,10 +91,10 @@ applications:
         - 5
         - 6
 relations:
-  - - "kubernetes-master:kube-api-endpoint"
-    - "kubeapi-load-balancer:apiserver"
-  - - "kubernetes-master:loadbalancer"
-    - "kubeapi-load-balancer:loadbalancer"
+  - - "kubernetes-master:loadbalancer-external"
+    - "kubeapi-load-balancer:lb-consumers"
+  - - "kubernetes-master:loadbalancer-internal"
+    - "kubeapi-load-balancer:lb-consumers"
   - - "kubernetes-master:kube-control"
     - "kubernetes-worker:kube-control"
   - - "kubernetes-master:certificates"
@@ -105,7 +105,5 @@ relations:
     - "etcd:db"
   - - "kubernetes-worker:certificates"
     - "easyrsa:client"
-  - - "kubernetes-worker:kube-api-endpoint"
-    - "kubeapi-load-balancer:website"
   - - "kubeapi-load-balancer:certificates"
     - "easyrsa:client"

fragments/k8s/cdk/bundle.yaml

@@ -47,10 +47,10 @@ applications:
       "gui-x": "800"
       "gui-y": "420"
 relations:
-  - - "kubernetes-master:kube-api-endpoint"
-    - "kubeapi-load-balancer:apiserver"
-  - - "kubernetes-master:loadbalancer"
-    - "kubeapi-load-balancer:loadbalancer"
+  - - "kubernetes-master:loadbalancer-external"
+    - "kubeapi-load-balancer:lb-consumers"
+  - - "kubernetes-master:loadbalancer-internal"
+    - "kubeapi-load-balancer:lb-consumers"
   - - "kubernetes-master:kube-control"
     - "kubernetes-worker:kube-control"
   - - "kubernetes-master:certificates"
@@ -61,7 +61,5 @@ relations:
     - "etcd:db"
   - - "kubernetes-worker:certificates"
     - "easyrsa:client"
-  - - "kubernetes-worker:kube-api-endpoint"
-    - "kubeapi-load-balancer:website"
   - - "kubeapi-load-balancer:certificates"
     - "easyrsa:client"

fragments/k8s/core/bundle.yaml

@@ -46,8 +46,6 @@ applications:
       "gui-x": "800"
       "gui-y": "420"
 relations:
-  - - "kubernetes-master:kube-api-endpoint"
-    - "kubernetes-worker:kube-api-endpoint"
   - - "kubernetes-master:kube-control"
     - "kubernetes-worker:kube-control"
   - - "kubernetes-master:certificates"