run jest tests on ubuntu-20.04-xl (github#28568)

* run jest tests on ubuntu-20.04-xl

* cpu debug info

* compare with unbuntu-latest

* tidy back up

Author: peterbe

.github/workflows/test.yml

@@ -23,9 +23,9 @@ concurrency:
 
 jobs:
   test:
-    # Run on self-hosted if the private repo or ubuntu-latest if the public repo
+    # Run on ubuntu-20.04-xl if the private repo or ubuntu-latest if the public repo
     # See pull # 17442 in the private repo for context
-    runs-on: ${{ fromJSON('["ubuntu-latest", "self-hosted"]')[github.repository == 'github/docs-internal'] }}
+    runs-on: ${{ fromJSON('["ubuntu-latest", "ubuntu-20.04-xl"]')[github.repository == 'github/docs-internal'] }}
     timeout-minutes: 60
     strategy:
       fail-fast: false