Remove upsert_issue_metrics feature flag

Remove feature flag for optimizing recording of issue metrics using
upsert

Changelog: other

app/models/issue.rb

@@ -586,14 +586,7 @@ class Issue < ApplicationRecord
 
   override :ensure_metrics
   def ensure_metrics
-    return Issue::Metrics.record!(self) if Feature.enabled?(:upsert_issue_metrics, default_enabled: :yaml)
-
-    if !association(:metrics).loaded? || metrics.blank?
-      metrics_record = Issue::Metrics.safe_find_or_create_by(issue: self)
-      self.metrics = metrics_record
-    end
-
-    metrics.record!
+    Issue::Metrics.record!(self)
   end
 
   def record_create_action

app/models/issue/metrics.rb

@@ -35,22 +35,4 @@ class Issue::Metrics < ApplicationRecord
       issue.labels.joins(:lists).exists?
     end
   end
-
-  def record!
-    if issue.milestone_id.present? && self.first_associated_with_milestone_at.blank?
-      self.first_associated_with_milestone_at = Time.current
-    end
-
-    if issue_assigned_to_list_label? && self.first_added_to_board_at.blank?
-      self.first_added_to_board_at = Time.current
-    end
-
-    self.save
-  end
-
-  private
-
-  def issue_assigned_to_list_label?
-    issue.labels.joins(:lists).exists?
-  end
 end

config/feature_flags/development/upsert_issue_metrics.yml

----
-name: upsert_issue_metrics
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/68509
-rollout_issue_url: 
-milestone: '14.3'
-type: development
-group: group::project management
-default_enabled: false

spec/models/issue/metrics_spec.rb

@@ -34,7 +34,7 @@ RSpec.describe Issue::Metrics do
     end
   end
 
-  shared_examples "when recording the default set of issue metrics on issue save" do
+  context "when recording the default set of issue metrics on issue save" do
     context "milestones" do
       it "records the first time an issue is associated with a milestone" do
         time = Time.current
@@ -81,20 +81,4 @@ RSpec.describe Issue::Metrics do
       end
     end
   end
-
-  context 'when upsert_issue_metrics is enabled' do
-    before do
-      stub_feature_flags(upsert_issue_metrics: true)
-    end
-
-    it_behaves_like 'when recording the default set of issue metrics on issue save'
-  end
-
-  context 'when upsert_issue_metrics is disabled' do
-    before do
-      stub_feature_flags(upsert_issue_metrics: false)
-    end
-
-    it_behaves_like 'when recording the default set of issue metrics on issue save'
-  end
 end