[cleanup] Remove unnecessary flags in test

The flags were added because scalar lowering was not implemented for the
instructions in the test. Now that scalar lowering is complete, we can
remove these flags.

Fixed: v8:11137
Change-Id: Ic7bdedbfe558fafebe98917fe4e6a7922203ba91
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2565078Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71474}

test/mjsunit/regress/wasm/regress-10831.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: --experimental-wasm-simd --enable-sse3 --enable-ssse3 --enable-sse4-1
+// Flags: --experimental-wasm-simd
 
 load('test/mjsunit/wasm/wasm-module-builder.js');