Update test suite for product tiers

Follow-up for
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/52703

The list of product tiers was recently updated. We want to reflect
these changes in the test suite.

spec/lib/gitlab/utils/markdown_spec.rb

@@ -53,33 +53,23 @@ RSpec.describe Gitlab::Utils::Markdown do
     end
 
     context 'when string has a product suffix' do
-      let(:string) { 'My Header (ULTIMATE)' }
-
-      it 'ignores a product suffix' do
-        is_expected.to eq 'my-header'
-      end
-
-      context 'with self modifier' do
-        let(:string) { 'My Header (PREMIUM SELF)' }
-
-        it 'ignores a product suffix' do
-          is_expected.to eq 'my-header'
-        end
-      end
-
-      context 'with "*" around a product suffix' do
-        let(:string) { 'My Header **(PREMIUM)**' }
-
-        it 'ignores a product suffix' do
-          is_expected.to eq 'my-header'
-        end
-      end
-
-      context 'with "*" around a product suffix and sass modifier' do
-        let(:string) { 'My Header **(PREMIUM SASS)**' }
-
-        it 'ignores a product suffix' do
-          is_expected.to eq 'my-header'
+      %w[CORE STARTER PREMIUM ULTIMATE FREE BRONZE SILVER GOLD].each do |tier|
+        ['', ' ONLY', ' SELF', ' SASS'].each do |modifier|
+          context "#{tier}#{modifier}" do
+            let(:string) { "My Header (#{tier}#{modifier})" }
+
+            it 'ignores a product suffix' do
+              is_expected.to eq 'my-header'
+            end
+
+            context 'with "*" around a product suffix' do
+              let(:string) { "My Header **(#{tier}#{modifier})**" }
+
+              it 'ignores a product suffix' do
+                is_expected.to eq 'my-header'
+              end
+            end
+          end
         end
       end
     end