[cleanup][disasm][x64] Fix some -Wshadow warnings

Bug: v8:12244,v8:12245
Change-Id: Iee80a34255a9c8ee5000719340a475331ab82942
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3254004Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77663}

test/cctest/test-disasm-x64.cc

@@ -46,7 +46,7 @@ namespace internal {
 
 TEST(DisasmX64) {
   Isolate* isolate = CcTest::i_isolate();
-  HandleScope scope(isolate);
+  HandleScope handle_scope(isolate);
   v8::internal::byte buffer[8192];
   Assembler assm(AssemblerOptions{},
                  ExternalAssemblerBuffer(buffer, sizeof buffer));