remove as_const option (on by default) in fbsource

Summary:
X-link: facebook/react-native#48227

This option is on by default in Flow v0.256

Reviewed By: gkz

Differential Revision: D67117062

fbshipit-source-id: 1595afe48178529ad43b33a215d84ff225cf9fa9

tools/hermes-parser/js/.flowconfig

@@ -26,7 +26,6 @@ module.name_mapper='^prettier-plugin-hermes-parser$' -> '<PROJECT_ROOT>/prettier
 component_syntax=true
 enums=true
 
-as_const=true
 experimental.natural_inference.exports.primitive_const=true
 
 [version]