Remove flaky tests from smoke suite

As part of efforts towards making review-qa-smoke
mandatory in https://gitlab.com/gitlab-com/www-gitlab-com/-/issues/11568

qa/qa/specs/features/browser_ui/4_verify/pipeline/create_and_process_pipeline_spec.rb

@@ -26,7 +26,8 @@ module QA
         runner.remove_via_api!
       end
 
-      it 'users creates a pipeline which gets processed', :smoke, testcase: 'https://gitlab.com/gitlab-org/quality/testcases/-/issues/1849' do
+      it 'users creates a pipeline which gets processed', testcase: 'https://gitlab.com/gitlab-org/quality/testcases/-/issues/1849' do
+        # TODO: Convert back to :smoke once proved to be stable. Related issue: https://gitlab.com/gitlab-org/gitlab/-/issues/300909
         tags_mismatch_status = Runtime::Feature.enabled?(feature_flag, project: project) ? :failed : :pending
 
         Flow::Login.sign_in

qa/qa/specs/features/browser_ui/6_release/pages/pages_pipeline_spec.rb

 # frozen_string_literal: true
 
 module QA
-  RSpec.describe 'Release', :smoke, :runner do
+  RSpec.describe 'Release', :runner do
+    # TODO: Convert back to :smoke once proved to be stable. Related issue: https://gitlab.com/gitlab-org/gitlab/-/issues/300906
     describe 'Pages' do
       let!(:project) do
         Resource::Project.fabricate_via_api! do |project|