Clear memoization of a stubbed object

This fixes succeeding specs that call pipeline_creation_step_histogram

spec/lib/gitlab/ci/pipeline/metrics_spec.rb

@@ -4,9 +4,15 @@ require 'spec_helper'
 
 RSpec.describe ::Gitlab::Ci::Pipeline::Metrics do
   describe '.pipeline_creation_step_duration_histogram' do
-    it 'adds the step to the step duration histogram' do
+    around do |example|
+      described_class.clear_memoization(:pipeline_creation_step_histogram)
+
+      example.run
+
       described_class.clear_memoization(:pipeline_creation_step_histogram)
+    end
 
+    it 'adds the step to the step duration histogram' do
       expect(::Gitlab::Metrics).to receive(:histogram)
         .with(
           :gitlab_ci_pipeline_creation_step_duration_seconds,

spec/lib/gitlab/ci/templates/Terraform/base_latest_gitlab_ci_yaml_spec.rb

@@ -19,7 +19,7 @@ RSpec.describe 'Terraform/Base.latest.gitlab-ci.yml' do
       allow(project).to receive(:default_branch).and_return(default_branch)
     end
 
-    it 'does not create any jobs', quarantine: 'https://gitlab.com/gitlab-org/gitlab/-/issues/339979' do
+    it 'does not create any jobs' do
       expect(build_names).to be_empty
     end
   end