CreatePipelineBuildsService would have created env

So we don't have to do it in CreateDeploymentService
Feedback:
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/11695#note_31322649

app/models/ci/build.rb

@@ -19,12 +19,6 @@ module Ci
       )
     end
 
-    def ensure_persisted_environment
-      persisted_environment ||
-        @persisted_environment =
-          project.environments.create(name: expanded_environment_name)
-    end
-
     serialize :options # rubocop:disable Cop/ActiverecordSerialize
     serialize :yaml_variables, Gitlab::Serializer::Ci::Variables # rubocop:disable Cop/ActiverecordSerialize
 

app/services/create_deployment_service.rb

@@ -42,7 +42,7 @@ class CreateDeploymentService
   end
 
   def environment
-    @environment ||= job.ensure_persisted_environment
+    @environment ||= job.persisted_environment
   end
 
   def environment_options

spec/models/ci/build_spec.rb

@@ -960,36 +960,6 @@ describe Ci::Build, :models do
     end
   end
 
-  describe '#ensure_persisted_environment' do
-    subject { job.ensure_persisted_environment }
-
-    let(:job) do
-      create(:ci_build,
-        ref: 'master',
-        environment: 'staging/$CI_COMMIT_REF_NAME')
-    end
-
-    context 'when there is no environment' do
-      it 'creates one by the expanded name' do
-        expect do
-          expect(subject.name).to eq('staging/master')
-        end.to change { Environment.count }.by(1)
-      end
-    end
-
-    context 'when there is already an environment' do
-      let!(:environment) do
-        create(:environment, project: job.project, name: 'staging/master')
-      end
-
-      it 'returns the existing environment' do
-        expect do
-          expect(subject).to eq(environment)
-        end.to change { Environment.count }.by(0)
-      end
-    end
-  end
-
   describe '#play' do
     let(:build) { create(:ci_build, :manual, pipeline: pipeline) }