Build/Test Tools: Test the new performance workflow regularly.

This adds the new performance measurement workflow introduced in [55459] to the one that tests old branches on a regular schedule.

This ensures it continues to work as expected over time, even if the branches with this workflow are not updated for a bit of time.

Props flixos90, joemcgill, desrosj.
See #57687.

git-svn-id: https://develop.svn.wordpress.org/trunk@55507 602fd350-edb4-49c9-b593-d223f7449a82

.github/workflows/test-old-branches.yml

@@ -65,6 +65,10 @@ jobs:
           - branch: '5.8'
             workflow: 'end-to-end-tests.yml'
 
+          # Performance testing was introduced in 6.2.
+          - branch: '6.2'
+            workflow: 'performance.yml'
+
     # Run all branches monthly, but only the currently supported one twice per month.
     steps:
       - name: Dispatch workflow run