chore(Pagehead): Move Pagehead component css module feature flag to ga (#5378)

* Move Pagehead component to ga

* Create cyan-eggs-sort.md

Author: jonrohan

.changeset/cyan-eggs-sort.md

@@ -0,0 +1,5 @@
+---
+"@primer/react": patch
+---
+
+Move Pagehead component css module feature flag to ga

packages/react/src/Pagehead/Pagehead.tsx

@@ -7,7 +7,7 @@ import {toggleStyledComponent} from '../internal/utils/toggleStyledComponent'
 import classes from './Pagehead.module.css'
 import {useFeatureFlag} from '../FeatureFlags'
 
-const CSS_MODULES_FEATURE_FLAG = 'primer_react_css_modules_staff'
+const CSS_MODULES_FEATURE_FLAG = 'primer_react_css_modules_ga'
 
 /**
  * @deprecated