[ci] use GitOps.ResourceManagement, as FabricBot is decommissioned (#8173)

Context: fb89198
Context: a0377cd
Context: 3918337
Context: https://aka.ms/gim/fabricbot
Context: https://microsoft.github.io/GitOps/policies/resource-management.html

Migrate away from `fabricbot.json` (fb89198, a0377cd, 3918337) to
`.github/policies/resourceManagement.yml`

Co-authored-by: microsoft-github-policy-service[bot] <77245923+microsoft-github-policy-service[bot]@users.noreply.github.com>

Author: microsoft-github-policy-service[bot]