E2E test: add tag external_ai_provider metadata to ai tests

qa/qa/specs/features/ee/browser_ui/10_govern/explain_this_vulnerability_spec.rb

 # frozen_string_literal: true
 
 module QA
-  RSpec.describe 'Govern', :runner, :external_api_calls,
+  RSpec.describe 'Govern', :runner, :external_api_calls, :external_ai_provider,
     only: { pipeline: %i[staging staging-canary canary production] },
     product_group: :threat_insights do
     describe 'Vulnerability Report' do

qa/qa/specs/features/ee/browser_ui/10_govern/resolve_this_vulnerability_spec.rb

 # frozen_string_literal: true
 
 module QA
-  RSpec.describe 'Govern', :runner, :external_api_calls,
+  RSpec.describe 'Govern', :runner, :external_api_calls, :external_ai_provider,
     only: { pipeline: %i[staging staging-canary canary production] },
     product_group: :threat_insights do
     describe 'Vulnerability Report' do