Mirrors the per-user delay pattern used in tests/conftest.py:all_oauth_tokens
(commit 963a504). Without it, all four Playwright browser contexts hit
Nextcloud's OIDC authorize endpoint simultaneously and the last users in
iteration order (charlie/diana) frequently time out on the consent screen
in CI, producing `TimeoutError: Timeout waiting for OAuth callback`.
Uses a 0.5s stagger locally and 10s in GITHUB_ACTIONS, matching the
existing fixture so behaviour stays consistent across the two parallel
fixtures.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>