[offthread] Disable compiler dispatcher tests

Disable the BackgroundCompileTask and CompilerDispatcher unittests when
--finalize-streaming-on-background is enabled. The inner function API to
concurrent compilation doesn't yet support off-thread finalization, so
these tests break under that configuration.

Bug: chromium:1011762
Change-Id: If8d8d8e814161668e12f309e8d69ef8e8a29ab4a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2502329
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70846}

test/unittests/compiler-dispatcher/compiler-dispatcher-unittest.cc

@@ -33,6 +33,8 @@ class CompilerDispatcherTestFlags {
     CHECK_NULL(save_flags_);
     save_flags_ = new SaveFlags();
     FLAG_single_threaded = true;
+    // TODO(leszeks): Support background finalization in compiler dispatcher.
+    FLAG_finalize_streaming_on_background = false;
     FlagList::EnforceFlagImplications();
     FLAG_compiler_dispatcher = true;
   }

test/unittests/tasks/background-compile-task-unittest.cc

@@ -35,6 +35,8 @@ class BackgroundCompileTaskTest : public TestWithNativeContext {
   static void SetUpTestCase() {
     CHECK_NULL(save_flags_);
     save_flags_ = new SaveFlags();
+    // TODO(leszeks): Support background finalization in compiler dispatcher.
+    FLAG_finalize_streaming_on_background = false;
     TestWithNativeContext::SetUpTestCase();
   }