Revert "Reland "[rab/gsab] Temporarily stage --harmony-rab-gsab to enable fuzzing""

This reverts commit df73fd60.

Reason for revert: Reverting before branch

Original change's description:
> Reland "[rab/gsab] Temporarily stage --harmony-rab-gsab to enable fuzzing"
>
> This reverts commit 24286b8e.
>
> Reason for revert: Re-staging the experimental flag for fuzzing
>
> Original change's description:
> > Revert "[rab/gsab] Temporarily stage --harmony-rab-gsab to enable fuzzing"
> >
> > This reverts commit b8f88be0.
> >
> > Reason: disabling an experimental feature in release branch
> >
> > Bug: v8:11111,v8:12870
> > Change-Id: I6fbd6bdb318c0d25e69c04db208a0d5f2b9ebbd7
> > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3647357
> > Auto-Submit: Marja Hölttä <marja@chromium.org>
> > Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> > Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
> > Cr-Commit-Position: refs/heads/main@{#80520}
>
> Bug: v8:11111,v8:12870
> Change-Id: I0a45ed5ce53010196949dda23773d152aa605846
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3647836
> Commit-Queue: Marja Hölttä <marja@chromium.org>
> Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
> Cr-Commit-Position: refs/heads/main@{#80576}

Bug: v8:11111,v8:12870
Change-Id: Ib32c1ba464dde7a5c8cc16f32680bad144bb4304
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3683358Reviewed-by: Lutz Vahl <vahl@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80888}

src/flags/flag-definitions.h

@@ -305,6 +305,8 @@ DEFINE_BOOL(harmony_shipping, true, "enable all shipped harmony features")
   V(harmony_weak_refs_with_cleanup_some,                                       \
     "harmony weak references with FinalizationRegistry.prototype.cleanupSome") \
   V(harmony_import_assertions, "harmony import assertions")                    \
+  V(harmony_rab_gsab,                                                          \
+    "harmony ResizableArrayBuffer / GrowableSharedArrayBuffer")                \
   V(harmony_temporal, "Temporal")                                              \
   V(harmony_shadow_realm, "harmony ShadowRealm")                               \
   V(harmony_struct, "harmony structs and shared structs")                      \
@@ -320,11 +322,8 @@ DEFINE_BOOL(harmony_shipping, true, "enable all shipped harmony features")
 #endif
 
 // Features that are complete (but still behind the --harmony flag).
-// --harmony-rab-gsab is staged temporarily to enable fuzzing.
-#define HARMONY_STAGED_BASE(V)                        \
-  V(harmony_array_grouping, "harmony array grouping") \
-  V(harmony_rab_gsab,                                 \
-    "harmony ResizableArrayBuffer / GrowableSharedArrayBuffer")
+#define HARMONY_STAGED_BASE(V) \
+  V(harmony_array_grouping, "harmony array grouping")
 
 #ifdef V8_INTL_SUPPORT
 #define HARMONY_STAGED(V) HARMONY_STAGED_BASE(V)