DEV: Skip two flaky system tests (#22651)

Why this change?

These tests have shown to be flaky and are being skipped for now while
we look into it.

spec/system/category_topics_spec.rb

@@ -7,6 +7,13 @@ describe "Viewing top topics on categories page", type: :system, js: true do
   fab!(:topic) { Fabricate(:topic, category: category) }
 
   it "displays and updates new counter" do
+    skip(<<~TEXT)
+    Flaky at the following step:
+
+    expect(category_list).to have_no_new_posts_badge
+       expected `#<PageObjects::Components::CategoryList:0x00007fe27a3d2340>.has_no_new_posts_badge?` to be truthy, got false
+    TEXT
+
     sign_in(user)
 
     visit("/categories")