S390: Add missing headers to disasm-s390-unittest

Modification is needed since after this CL:
https://crrev.com/c/3676642

Bug: v8:12781
Change-Id: Icb2644c9cd6f20e37c4b0ba0c4b861417c84b7f1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3679980Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Farazmand <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/main@{#80871}

test/unittests/assembler/disasm-s390-unittest.cc

@@ -34,7 +34,8 @@
 #include "src/diagnostics/disassembler.h"
 #include "src/execution/frames-inl.h"
 #include "src/init/v8.h"
-#include "test/cctest/cctest.h"
+#include "test/unittests/test-utils.h"
+#include "testing/gtest/include/gtest/gtest.h"
 
 namespace v8 {
 namespace internal {