Do not cancel jobs on main when new commits are pushed

Summary:
Last month, during the migration to GHA, we decided to reimplement the same behavior we had in CCI: when a new commit comes in, we stop executing tests on the previous one.

This behavior is great to save money, but on main it has the side effect that it makes it hard to detect when the ci was broken.

\With this change, we want to disable this behvior on main while keeping it in PRs.

After this change, when a new commit arrives on main, the previous jobs will not be interrupted

## Changelog
[Internal] - Do not cancel jobs on main when new commits are pushed.

Reviewed By: cortinico, blakef

Differential Revision: D60822657

fbshipit-source-id: 38561438f2e2850a94220d732cd73a09d04e8b81

.github/workflows/test-all.yml

@@ -10,7 +10,7 @@ on:
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
-  cancel-in-progress: true # cancel previous runs
+  cancel-in-progress: ${{ github.ref != 'refs/heads/main' && !contains(github.ref,  'stable')}}
 
 jobs:
   set_release_type: