Revert "[baseline] Enable SP on the heap on future"

This reverts commit 20dc4dcc.

Reason for revert: We're killing SP on the heap.

Original change's description:
> [baseline] Enable SP on the heap on future
>
> Bug: v8:11872
> Change-Id: Iaaf3ed68950a6a9fe60f91d73be8a0fbc17e1116
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3129424
> Commit-Queue: Victor Gomes <victorgomes@chromium.org>
> Commit-Queue: Leszek Swirski <leszeks@chromium.org>
> Auto-Submit: Victor Gomes <victorgomes@chromium.org>
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#76578}

Bug: v8:11872, v8:12158
Change-Id: Ib12912250013cdebeca1597f6c9dcd4f763b7a4a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3135660
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76624}

src/flags/flag-definitions.h

@@ -506,7 +506,6 @@ DEFINE_WEAK_IMPLICATION(future, turbo_inline_js_wasm_calls)
 #if ENABLE_SPARKPLUG
 DEFINE_WEAK_IMPLICATION(future, sparkplug)
 DEFINE_WEAK_IMPLICATION(future, flush_baseline_code)
-DEFINE_WEAK_IMPLICATION(future, sparkplug_on_heap)
 #endif
 #if V8_SHORT_BUILTIN_CALLS
 DEFINE_WEAK_IMPLICATION(future, short_builtin_calls)