Fix Flow errors (#20696)

Summary:
Revert change to flow strict-local in OSS.
Pull Request resolved: https://github.com/facebook/react-native/pull/20696

Differential Revision: D9367630

Pulled By: hramos

fbshipit-source-id: 17e4d1ab6d00b2e14033b223d878d5fcd1c098f4

local-cli/bundle/types.flow.js

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  *
  * @format
- * @flow strict-local
+ * @flow
  */
 
 'use strict';

local-cli/server/server.js

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  *
  * @format
- * @flow strict-local
+ * @flow
  */
 
 'use strict';

local-cli/templates/HelloWorld/App.js

@@ -3,7 +3,7 @@
  * https://github.com/facebook/react-native
  *
  * @format
- * @flow strict-local
+ * @flow
  */
 
 import React, {Component} from 'react';