Remove use_insert_all_in_internal_id feature flag

Creates internal ID records without using a subtransaction

Also changes, insert_all to insert since they're just the same under the
hood

Changelog: other

app/models/internal_id.rb

@@ -223,7 +223,6 @@ class InternalId < ApplicationRecord
     # If another process was faster in doing this, we'll end up with that record
     # when we do the lookup after the insert.
     def create_record
-      if Feature.enabled?(:use_insert_all_in_internal_id, default_enabled: :yaml)
       scope[:project].save! if scope[:project] && !scope[:project].persisted?
       scope[:namespace].save! if scope[:namespace] && !scope[:namespace].persisted?
 
@@ -234,24 +233,11 @@ class InternalId < ApplicationRecord
         last_value: initial_value(subject, scope)
       }
 
-        InternalId.insert_all([attributes])
+      InternalId.insert(attributes)
 
-        lookup
-      else
-        begin
-          subject.transaction(requires_new: true) do # rubocop:disable Performance/ActiveRecordSubtransactions
-            InternalId.create!(
-              **scope,
-              usage: usage_value,
-              last_value: initial_value(subject, scope)
-            )
-          end
-        rescue ActiveRecord::RecordNotUnique
       lookup
     end
   end
-    end
-  end
 
   class ImplicitlyLockingInternalIdGenerator
     # Generate next internal id for a given scope and usage.
@@ -344,7 +330,6 @@ class InternalId < ApplicationRecord
     end
 
     def create_record!(subject, scope, usage, value)
-      if Feature.enabled?(:use_insert_all_in_internal_id, default_enabled: :yaml)
       scope[:project].save! if scope[:project] && !scope[:project].persisted?
       scope[:namespace].save! if scope[:namespace] && !scope[:namespace].persisted?
 
@@ -355,21 +340,11 @@ class InternalId < ApplicationRecord
         last_value: value
       }
 
-        result = InternalId.insert_all([attributes])
+      result = InternalId.insert(attributes)
 
       raise RecordAlreadyExists if result.empty?
 
       value
-      else
-        begin
-          subject.transaction(requires_new: true) do # rubocop:disable Performance/ActiveRecordSubtransactions
-            internal_id = InternalId.create!(**scope, usage: usage, last_value: value)
-            internal_id.last_value
-          end
-        rescue ActiveRecord::RecordNotUnique
-          raise RecordAlreadyExists
-        end
-      end
     end
 
     def arel_table

config/feature_flags/development/use_insert_all_in_internal_id.yml

----
-name: use_insert_all_in_internal_id
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/68617
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/339141
-milestone: '14.3'
-type: development
-group: group::project management
-default_enabled: false

spec/models/internal_id_spec.rb

@@ -243,44 +243,16 @@ RSpec.describe InternalId do
       stub_feature_flags(generate_iids_without_explicit_locking: false)
     end
 
-    context 'when the insert all feature flag is enabled' do
-      before do
-        stub_feature_flags(use_insert_all_in_internal_id: true)
-      end
-
-      it_behaves_like 'a monotonically increasing id generator'
-    end
-
-    context 'when the insert all feature flag is disabled' do
-      before do
-        stub_feature_flags(use_insert_all_in_internal_id: false)
-      end
-
     it_behaves_like 'a monotonically increasing id generator'
   end
-  end
 
   context 'when the explicit locking feature flag is enabled' do
     before do
       stub_feature_flags(generate_iids_without_explicit_locking: true)
     end
 
-    context 'when the insert all feature flag is enabled' do
-      before do
-        stub_feature_flags(use_insert_all_in_internal_id: true)
-      end
-
-      it_behaves_like 'a monotonically increasing id generator'
-    end
-
-    context 'when the insert all feature flag is disabled' do
-      before do
-        stub_feature_flags(use_insert_all_in_internal_id: false)
-      end
-
     it_behaves_like 'a monotonically increasing id generator'
   end
-  end
 
   describe '#increment_and_save!' do
     let(:id) { create(:internal_id) }