INF-474: Migrate GitHub Actions runners to vars.RUNNER_STANDARD

- Migrated hardcoded runner values to organization variables
- Changed ubuntu-latest → \${{ vars.RUNNER_STANDARD }}
- Changed self-hosted → \${{ vars.RUNNER_STANDARD }}

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: espensb

.github/workflows/release.yml

@@ -4,7 +4,7 @@ on:
     types: [published]
 jobs:
   pypi:
-    runs-on: ubuntu-latest
+    runs-on: ${{ vars.RUNNER_STANDARD }}
     steps:
       - name: Checkout
         uses: actions/checkout@v4