Don't run test validation off main branch (#1644)

Summary:
Pull Request resolved: #1644

Because Chrome behaviors can change

Reviewed By: cortinico

Differential Revision: D56088135

fbshipit-source-id: 7f760786dde061df9af034368e2184117e6e6846

Author: NickGerleman

.github/workflows/validate-tests.yml

@@ -5,7 +5,6 @@ on:
   push:
     branches:
       - main
-      - 'release-*'
   workflow_dispatch:
 
 jobs: