remove default option experimental.global_find_ref=true (#44515)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/44515

this has been the default for a while

Changelog: [Internal]

Reviewed By: SamChou19815

Differential Revision: D57195561

fbshipit-source-id: b441d972134dba754d714ae5694d94537707ded3

.flowconfig

@@ -35,7 +35,6 @@ packages/react-native/interface.js
 packages/react-native/flow/
 
 [options]
-experimental.global_find_ref=true
 enums=true
 casting_syntax=both