Indent "idempotency" in protoc-gen-connect-es

[timostamm]

Our indentation is a bit off (test.proto):

    cacheableUnaryCall: {
      name: "CacheableUnaryCall",
      I: SimpleRequest,
      O: SimpleResponse,
      kind: MethodKind.Unary,
    idempotency: MethodIdempotency.NoSideEffects,
    },

This adds two spaces to the TS output.