Enable `vue_project_members_list` feature flag by default

app/controllers/projects/project_members_controller.rb

@@ -9,7 +9,7 @@ class Projects::ProjectMembersController < Projects::ApplicationController
   before_action :authorize_admin_project_member!, except: [:index, :leave, :request_access]
 
   before_action do
-    push_frontend_feature_flag(:vue_project_members_list, @project)
+    push_frontend_feature_flag(:vue_project_members_list, @project, default_enabled: :yaml)
   end
 
   feature_category :authentication_and_authorization

app/views/projects/project_members/index.html.haml

 - page_title _("Members")
 - group = @project.group
-- vue_project_members_list_enabled = Feature.enabled?(:vue_project_members_list, @project)
+- vue_project_members_list_enabled = Feature.enabled?(:vue_project_members_list, @project, default_enabled: :yaml)
 
 .js-remove-member-modal
 .row.gl-mt-3

changelogs/unreleased/299954-feature-flag-rollout-of-vue_project_members_list.yml

+---
+title: Improve project members management, filtering, and sorting
+merge_request: 53935
+author:
+type: changed

config/feature_flags/development/vue_project_members_list.yml

@@ -5,4 +5,4 @@ rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/299954
 milestone: '13.9'
 type: development
 group: group::access
-default_enabled: false
+default_enabled: true