Enable frozen string for spec/presenters

Partially addresses:

https://gitlab.com/gitlab-org/gitlab/issues/27703

spec/presenters/ci/bridge_presenter_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Ci::BridgePresenter do

spec/presenters/ci/build_presenter_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Ci::BuildPresenter do

spec/presenters/ci/build_runner_presenter_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Ci::BuildRunnerPresenter do

spec/presenters/ci/group_variable_presenter_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Ci::GroupVariablePresenter do

spec/presenters/ci/pipeline_presenter_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Ci::PipelinePresenter do

spec/presenters/ci/trigger_presenter_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Ci::TriggerPresenter do

spec/presenters/ci/variable_presenter_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Ci::VariablePresenter do

spec/presenters/clusters/cluster_presenter_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Clusters::ClusterPresenter do

spec/presenters/commit_status_presenter_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe CommitStatusPresenter do

spec/presenters/conversational_development_index/metric_presenter_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe ConversationalDevelopmentIndex::MetricPresenter do

spec/presenters/group_member_presenter_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe GroupMemberPresenter do

spec/presenters/merge_request_presenter_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe MergeRequestPresenter do

spec/presenters/project_member_presenter_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe ProjectMemberPresenter do

spec/presenters/project_presenter_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe ProjectPresenter do

spec/presenters/projects/settings/deploy_keys_presenter_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Projects::Settings::DeployKeysPresenter do