Bugfix/25354 /etc/hosts gone after reboot

[rb-aguzman]

What does this fix do?

Fixes /etc/hosts file corruption during concurrent chef-client runs.

Changes:

• Replace sed -i with atomic write using grep -v + mv to prevent race condition

Files changed

• resources/providers/config.rb — use atomic write for /etc/hosts modification

Redmine Ticket

https://redmine.redborder.lan/issues/25392

How to test

1. Follow steps from Bug #25354 investigation (Task #25377)
2. Run chef-client multiple times concurrently
3. Verify /etc/hosts content is preserved after reboot