fix: update workflow concurrency groups to enable run cancellation

- Refactor concurrency settings in `e2e-tests-split.yml` and `codecov-upload.yml` to remove SHA and run_id from group strings, allowing for proper cancellation of in-progress runs.
- Ensure that new pushes to the same branch cancel any ongoing workflow runs, improving CI efficiency and reducing queue times.

.github/workflows/e2e-tests-split.yml

@@ -95,7 +95,7 @@ env:
   CI_LOG_LEVEL: 'verbose'
 
 concurrency:
-  group: e2e-split-${{ github.workflow }}-${{ github.ref }}-${{ github.event.pull_request.head.sha || github.sha }}
+  group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true
 
 jobs: