UI update headless chrome flags to fix 'yarn run test:oss' (#8035)

* UI update headless chrome flags to fix ember/chrome crash in test

* UI update references from test-oss to test:oss

* UI removed disable-gpu flag from headless Chrome

* UI and also remove the comment

ui/testem.js

@@ -10,7 +10,6 @@ const config = {
         // --no-sandbox is needed when running Chrome inside a container
         process.env.CI ? '--no-sandbox' : null,
         '--headless',
-        '--disable-gpu',
         '--disable-software-rasterizer',
         '--mute-audio',
         '--remote-debugging-port=0',