Fix uniqueDebuggerId so that it returns debugger id, not the context id

Bug: chromium:1240663
Change-Id: I133e3de012b08666c767478b8ad6fd7bf7c0fa35
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3679098Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Auto-Submit: Danil Somsikov <dsv@chromium.org>
Commit-Queue: Danil Somsikov <dsv@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80864}

src/inspector/v8-inspector-impl.cc

@@ -187,7 +187,8 @@ v8::MaybeLocal<v8::Context> V8InspectorImpl::contextById(int contextId) {
 V8DebuggerId V8InspectorImpl::uniqueDebuggerId(int contextId) {
   InspectedContext* context = getContext(contextId);
   internal::V8DebuggerId unique_id;
-  if (context) unique_id = context->uniqueId();
+  if (context) unique_id = m_debugger->debuggerIdFor(context->contextGroupId());
+
   return unique_id.toV8DebuggerId();
 }