Remove github_importer_use_diff_note_with_suggestions feature flag

Changelog: changed

config/feature_flags/development/github_importer_use_diff_note_with_suggestions.yml

----
-name: github_importer_use_diff_note_with_suggestions
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/71765
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/344309
-milestone: '14.5'
-type: development
-group: group::import
-default_enabled: true

doc/user/project/import/github.md

@@ -26,7 +26,7 @@ The following aspects of a project are imported:
 - Regular issue and pull request comments
 - [Git Large File Storage (LFS) Objects](../../../topics/git/lfs/index.md)
 - Pull request comments replies in discussions ([GitLab.com & 14.5+](https://gitlab.com/gitlab-org/gitlab/-/issues/336596))
-- Diff Notes suggestions ([GitLab.com & 14.7+](https://gitlab.com/gitlab-org/gitlab/-/issues/340624)) [with a flag](../../../administration/feature_flags.md) named `github_importer_use_diff_note_with_suggestions`. Enabled by default.
+- Diff Notes suggestions ([GitLab.com & 14.7+](https://gitlab.com/gitlab-org/gitlab/-/issues/340624))
 
 References to pull requests and issues are preserved (GitLab.com & 8.7+), and
 each imported repository maintains visibility level unless that [visibility

lib/gitlab/github_import/importer/diff_note_importer.rb

@@ -26,7 +26,7 @@ module Gitlab
           # because it cannot use the BulkImporting strategy, which skips
           # callbacks and validations. For this reason, notes that don't have
           # suggestions are still imported with LegacyDiffNote
-          if import_with_diff_note?
+          if note.contains_suggestion?
             import_with_diff_note
           else
             import_with_legacy_diff_note
@@ -48,17 +48,6 @@ module Gitlab
 
         attr_reader :note, :project, :client, :author_id, :author_found
 
-        def import_with_diff_note?
-          note.contains_suggestion? && use_diff_note_with_suggestions_enabled?
-        end
-
-        def use_diff_note_with_suggestions_enabled?
-          Feature.enabled?(
-            :github_importer_use_diff_note_with_suggestions,
-            default_enabled: :yaml
-          )
-        end
-
         def build_author_attributes
           @author_id, @author_found = user_finder.author_id_for(note)
         end

spec/lib/gitlab/github_import/importer/diff_note_importer_spec.rb

@@ -119,48 +119,6 @@ RSpec.describe Gitlab::GithubImport::Importer::DiffNoteImporter, :aggregate_fail
           .and_return(discussion_id)
       end
 
-      context 'when github_importer_use_diff_note_with_suggestions is disabled' do
-        before do
-          stub_feature_flags(github_importer_use_diff_note_with_suggestions: false)
-        end
-
-        it_behaves_like 'diff notes without suggestion'
-
-        context 'when the note has suggestions' do
-          let(:note_body) do
-            <<~EOB
-            Suggestion:
-            ```suggestion
-            what do you think to do it like this
-            ```
-            EOB
-          end
-
-          it 'imports the note' do
-            stub_user_finder(user.id, true)
-
-            expect { subject.execute }
-              .to change(LegacyDiffNote, :count)
-              .and not_change(DiffNote, :count)
-
-            note = project.notes.diff_notes.take
-            expect(note).to be_valid
-            expect(note.note)
-              .to eq <<~NOTE
-              Suggestion:
-              ```suggestion:-0+0
-              what do you think to do it like this
-              ```
-              NOTE
-          end
-        end
-      end
-
-      context 'when github_importer_use_diff_note_with_suggestions is enabled' do
-        before do
-          stub_feature_flags(github_importer_use_diff_note_with_suggestions: true)
-        end
-
       it_behaves_like 'diff notes without suggestion'
 
       context 'when the note has suggestions' do
@@ -240,7 +198,6 @@ RSpec.describe Gitlab::GithubImport::Importer::DiffNoteImporter, :aggregate_fail
       end
     end
   end
-  end
 
   def stub_user_finder(user, found)
     expect_next_instance_of(Gitlab::GithubImport::UserFinder) do |finder|