[be] Remove unused validateRefAccessDuringRenderFunctionExpressions flag

I had split this up from the main validation since function validation was less 
precise; now that previous PRs fix the false positives we can remove this extra 
flag.

compiler/packages/babel-plugin-react-forget/src/HIR/Environment.ts

@@ -172,14 +172,6 @@ const EnvironmentConfigSchema = z.object({
   // Validate that ref values (`ref.current`) are not accessed during render.
   validateRefAccessDuringRender: z.boolean().default(false),
 
-  /**
-   * Extension of validateRefAccessDuringRender that validates that refs are not accessed during
-   * render indirectly by calling function expressions which access the ref.
-   *
-   * This validation has known issues and is not yet recommended
-   */
-  validateRefAccessDuringRenderFunctionExpressions: z.boolean().default(false),
-
   /*
    * Validates that setState is not unconditionally called during render, as it can lead to
    * infinite loops.

compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/error.invalid-aliased-ref-in-callback-invoked-during-render-.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @validateRefAccessDuringRender @validateRefAccessDuringRenderFunctionExpressions
+// @validateRefAccessDuringRender
 function Component(props) {
   const ref = useRef(null);
   const renderItem = (item) => {

compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/error.invalid-aliased-ref-in-callback-invoked-during-render-.js

@@ -1,4 +1,4 @@
-// @validateRefAccessDuringRender @validateRefAccessDuringRenderFunctionExpressions
+// @validateRefAccessDuringRender
 function Component(props) {
   const ref = useRef(null);
   const renderItem = (item) => {

compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/error.invalid-ref-in-callback-invoked-during-render.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @validateRefAccessDuringRender @validateRefAccessDuringRenderFunctionExpressions
+// @validateRefAccessDuringRender
 function Component(props) {
   const ref = useRef(null);
   const renderItem = (item) => {

compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/error.invalid-ref-in-callback-invoked-during-render.js

@@ -1,4 +1,4 @@
-// @validateRefAccessDuringRender @validateRefAccessDuringRenderFunctionExpressions
+// @validateRefAccessDuringRender
 function Component(props) {
   const ref = useRef(null);
   const renderItem = (item) => {