Remove ci_pipeline_latest feature flag

This feature flag was introduced in 13.2 and is now ready for removal

Changelog: removed

app/models/ci/pipeline.rb

@@ -610,8 +610,6 @@ def retry_failed(current_user)
     # rubocop: enable CodeReuse/ServiceClass
     def lazy_ref_commit
-      return unless ::Gitlab::Ci::Features.pipeline_latest?
-
       BatchLoader.for(ref).batch do |refs, loader|
         next unless project.repository_exists?
@@ -623,11 +621,6 @@ def lazy_ref_commit
     def latest?
       return false unless git_ref && commit.present?
-
-      unless ::Gitlab::Ci::Features.pipeline_latest?
-        return project.commit(git_ref) == commit
-      end
-
       return false if lazy_ref_commit.nil?
       lazy_ref_commit.id == commit.id

config/feature_flags/development/ci_pipeline_latest.yml

----
-name: ci_pipeline_latest
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/34160
-rollout_issue_url: 
-milestone: '13.2'
-type: development
-group: group::pipeline execution
-default_enabled: true

lib/gitlab/ci/features.rb

@@ -10,10 +10,6 @@ def self.artifacts_exclude_enabled?
         ::Feature.enabled?(:ci_artifacts_exclude, default_enabled: true)
       end
-      def self.pipeline_latest?
-        ::Feature.enabled?(:ci_pipeline_latest, default_enabled: true)
-      end
-
       def self.pipeline_status_omit_commit_sha_in_cache_key?(project)
         Feature.enabled?(:ci_pipeline_status_omit_commit_sha_in_cache_key, project, default_enabled: true)
       end