Disable medium test by default with older release branches

Signed-off-by: Dan McPherson <[email protected]>

Author: Dan McPherson

.github/workflows/e2e-nvidia-a10g-x1.yml

@@ -12,7 +12,6 @@ on:
   pull_request_target:
     branches:
       - main
-      - release-*
     paths:
       # note this should match the merging criteria in 'mergify.yml'
       - '**.py'