Use newer metro language: blacklistRE -> blockList (#30342)

Summary:
An [update to `metro`](facebook/metro@94c0b54#diff-1a3c1a959bb8c4e2e9743c03cb7a6d0c56648ffcfe129a11b9090bfc139622dd) which landed in metro 0.60 (RN 0.64+) deprecates the config `blacklistRE`, renaming it to `blockList`. Although the former is still supported it now generates a deprecation warning.

## Changelog

[General] [Fixed] - Update metro config language to `blockList`

Pull Request resolved: #30342

Test Plan: Confirm that the config is still respected (`/buck-out/` should be excluded), and that no deprecation warning is issued.

Reviewed By: lunaleaps

Differential Revision: D31380163

Pulled By: motiz88

fbshipit-source-id: f64cff30690f0252fafd4eac254a8c2278c4ac2f

metro.config.js

@@ -19,7 +19,7 @@ const getPolyfills = require('./rn-get-polyfills');
 module.exports = {
   resolver: {
     // $FlowFixMe[signature-verification-failure] Can't infer RegExp type.
-    blacklistRE: /buck-out/,
+    blockList: /buck-out/,
     extraNodeModules: {
       'react-native': __dirname,
     },