DEV: Run tests with new chrome headless (#21684)

New headless shares the same implementation as the chrome browser
instead of being a separate implementation of its own.

See https://developer.chrome.com/articles/new-headless/ for more
details

Co-authored-by: Rafael dos Santos Silva <xfalcox@gmail.com>

app/assets/javascripts/discourse/testem.js

@@ -96,7 +96,7 @@ module.exports = {
     Chrome: [
       // --no-sandbox is needed when running Chrome inside a container
       process.env.CI ? "--no-sandbox" : null,
-      "--headless",
+      "--headless=new",
       "--disable-dev-shm-usage",
       "--disable-software-rasterizer",
       "--mute-audio",

spec/rails_helper.rb

@@ -297,7 +297,7 @@ RSpec.configure do |config|
     end
 
     Capybara.register_driver :selenium_chrome_headless do |app|
-      chrome_browser_options.add_argument("--headless")
+      chrome_browser_options.add_argument("--headless=new")
 
       Capybara::Selenium::Driver.new(app, browser: :chrome, options: chrome_browser_options)
     end
@@ -319,7 +319,7 @@ RSpec.configure do |config|
     end
 
     Capybara.register_driver :selenium_mobile_chrome_headless do |app|
-      mobile_chrome_browser_options.add_argument("--headless")
+      mobile_chrome_browser_options.add_argument("--headless=new")
       Capybara::Selenium::Driver.new(app, browser: :chrome, options: mobile_chrome_browser_options)
     end
 

test/run-qunit.js

@@ -37,7 +37,7 @@ async function runAllTests() {
     const options = {
       chromeFlags: [
         "--disable-gpu",
-        "--headless",
+        "--headless=new",
         "--no-sandbox",
         "--disable-dev-shm-usage",
         "--mute-audio",