Fix CI concurrency: prevent test cancellation on main branch (#15188)

## Problem
The concurrency rules in CI workflows were cancelling in-progress test
runs even on the main branch. This caused inconsistent check counts when
multiple commits were pushed in quick succession.

## Solution
Updated `cancel-in-progress` in all CI workflows to be conditional:
- **On main branch**: Tests run to completion (no cancellation)
- **On feature branches**: Tests are cancelled when new commits are
pushed (saves CI resources)

## Changes
Modified 11 workflow files to use:
```yaml
cancel-in-progress: ${{ github.ref != 'refs/heads/main' }}
```

This ensures every commit to main gets fully tested while maintaining
efficiency on feature branches.

.github/workflows/ci-website.yaml

@@ -12,7 +12,7 @@ on:
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
-  cancel-in-progress: true
+  cancel-in-progress: ${{ github.ref != 'refs/heads/main' }}
 
 jobs:
   changed-files-check: