Customize log level in Fantom output (#48263)

Summary:
Pull Request resolved: #48263

Changelog: [internal]

Customize log level in Fantom based on flag in runner.js.

Reviewed By: javache

Differential Revision: D67199970

fbshipit-source-id: 31cdd2eaeee8e7ab4c8985661b35822d78d0457b

packages/react-native-fantom/runner/runner.js

@@ -189,6 +189,8 @@ module.exports = async function runTest(
       : testBytecodeBundlePath,
     '--featureFlags',
     JSON.stringify(testConfig.flags.common),
+    '--minLogLevel',
+    PRINT_FANTOM_OUTPUT ? 'info' : 'error',
   ]);
 
   if (rnTesterCommandResult.status !== 0) {