metropolis: remove stutter in ClusterConfiguration.KubernetesConfig

We already know this is a config (it lives in ClusterConfiguration), no
need to call that a config again.

This doesn't break any compatibility yet as field names are not (yet)
under a stability guarantee.

Change-Id: Ib6492d1c8303cbd0620b979b8047ec9757e301c0
Reviewed-on: https://review.monogon.dev/c/monogon/+/3594
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
Tested-by: Jenkins CI
diff --git a/metropolis/proto/common/common.proto b/metropolis/proto/common/common.proto
index 50ea4e4..2f23e08 100644
--- a/metropolis/proto/common/common.proto
+++ b/metropolis/proto/common/common.proto
@@ -332,7 +332,7 @@
     }
     StorageSecurityPolicy storage_security_policy = 2;
 
-    message KubernetesConfig {
+    message Kubernetes {
         message NodeLabelsToSynchronize {
             // Node labels matching this regexp will be synchronized.
             //
@@ -362,7 +362,7 @@
         // influenced by these rules.
         repeated NodeLabelsToSynchronize node_labels_to_synchronize = 3;
     }
-    KubernetesConfig kubernetes_config = 3;
+    Kubernetes kubernetes = 3;
 }
 
 // NodeTPMUsage describes whether a node has a TPM2.0 and if it is/should be