metropolis/pkg/(event|pki): remove dependency to consensus/client

We are currently depending on the consensus client, even when we just
need a plain etcd client. This change removes the dependency by adding
a ThinClient interface that wraps KV amd Watcher from clientv3.

Change-Id: I33994ab35ebb3a63c9dda4b588b7f529535e3083
Reviewed-on: https://review.monogon.dev/c/monogon/+/3082
Tested-by: Jenkins CI
Reviewed-by: Serge Bazanski <serge@monogon.tech>
diff --git a/metropolis/pkg/pki/crl_test.go b/metropolis/pkg/pki/crl_test.go
index 8f9cf5d..e47eab9 100644
--- a/metropolis/pkg/pki/crl_test.go
+++ b/metropolis/pkg/pki/crl_test.go
@@ -7,8 +7,6 @@
 
 	"go.etcd.io/etcd/client/pkg/v3/testutil"
 	"go.etcd.io/etcd/tests/v3/integration"
-
-	"source.monogon.dev/metropolis/node/core/consensus/client"
 )
 
 // TestRevoke exercises the CRL revocation and watching functionality of a CA
@@ -19,7 +17,7 @@
 	cluster := integration.NewClusterV3(tb, &integration.ClusterConfig{
 		Size: 1,
 	})
-	cl := client.NewLocal(cluster.Client(0))
+	cl := cluster.Client(0)
 	defer cluster.Terminate(tb)
 	ctx, ctxC := context.WithCancel(context.Background())
 	defer ctxC()