Remove daily config-sync workflow — source repo configs-js is archived

[ferencsarai]

This repo runs a daily cron workflow (.github/workflows/configs_sync.yaml, using
ethersphere/repo-sync-action@v1) that syncs shared tooling config from
ethersphere/configs-js.

That source repo is no longer maintained:

• Last commit to configs-js was in 2022.
• The ethersphere/configs-js repository
  was archived by the owner on May 12, 2026, and is now read-only.

Since the source is archived, this workflow can no longer receive any updates —
it's a daily no-op job that only burns CI minutes.