[eprh] Remove __EXPERIMENTAL__

`__EXPERIMENTAL__` flag doesn't have any use outside of the React repo. Let's remove these flags for now.

Author: poteto

compiler/packages/eslint-plugin-react-hooks/src/rules/ExhaustiveDeps.ts

@@ -2056,10 +2056,7 @@ function isAncestorNodeOf(a: Node, b: Node): boolean {
 }
 
 function isUseEffectEventIdentifier(node: Node): boolean {
-  if (__EXPERIMENTAL__) {
-    return node.type === 'Identifier' && node.name === 'useEffectEvent';
-  }
-  return false;
+  return node.type === 'Identifier' && node.name === 'useEffectEvent';
 }
 
 function getUnknownDependenciesMessage(reactiveHookName: string): string {

compiler/packages/eslint-plugin-react-hooks/src/rules/RulesOfHooks.ts

@@ -109,10 +109,7 @@ function isInsideDoWhileLoop(node: Node | undefined): node is DoWhileStatement {
 }
 
 function isUseEffectEventIdentifier(node: Node): boolean {
-  if (__EXPERIMENTAL__) {
-    return node.type === 'Identifier' && node.name === 'useEffectEvent';
-  }
-  return false;
+  return node.type === 'Identifier' && node.name === 'useEffectEvent';
 }
 
 function isUseIdentifier(node: Node): boolean {