tidy: dont double encode peer ID in tokens if same as key ID

internal/metadata/id_token_server.go

@@ -86,7 +86,14 @@ func (i *IDTokenServer) issueToken(w http.ResponseWriter, r *http.Request) {
 			Expiry:    jwt.NewNumericDate(Now().UTC().Add(5 * time.Minute)),
 			NotBefore: jwt.NewNumericDate(Now().UTC()),
 			IssuedAt:  jwt.NewNumericDate(Now().UTC()),
-			ID:        peerkey.ID(),
+			ID: func() string {
+				if info.Peer.GetId() == peerkey.ID() {
+					// Don't include the ID if it's the same as the subject.
+					// Saves space and makes it easier to read.
+					return ":subject"
+				}
+				return peerkey.ID()
+			}(),
 		},
 		Groups: []string{},
 	}