Revert "Fix map-constructor-entry-side-effect2 test"

This reverts commit 337d53e6.

Reason for revert: <REASONING>

Original change's description:
> Fix map-constructor-entry-side-effect2 test
>
> Bytecode flushing interferes with IsOptimized expectations.
>
> Bug: v8:7790,v8:11939
> Change-Id: I4aaf827cb198d0a93f18e106a95d72b143c79dfc
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2999092
> Commit-Queue: Jakob Gruber <jgruber@chromium.org>
> Commit-Queue: Sathya Gunasekaran  <gsathya@chromium.org>
> Auto-Submit: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#75508}

Bug: v8:7790,v8:11939
Change-Id: Ie85acc3ec98a823186ecfb982f1d5310bce81d7b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3000923
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75510}

test/mjsunit/es6/map-constructor-entry-side-effect2.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --allow-natives-syntax --opt --no-flush-bytecode
+// Flags: --allow-natives-syntax --opt
 
 function TestMapConstructorEntrySideEffect(ctor) {
   const originalPrototypeSet = ctor.prototype.set;