FabricBot: Onboarding to GitOps.ResourceManagement because of FabricBot decommissioning (#760)

* Add prIssueManagement.yml to onboard repo to GitOps.ResourceManagement as FabricBot replacement

Owners of the FabricBot configuration should have received email notification. The same information contained in the email is published internally at: https://aka.ms/gim/fabricbot. Details on the replacement service and the syntax of the new yaml configuration file is available publicly at: https://microsoft.github.io/GitOps/policies/resource-management.html

Please review and merge this PR to complete the process of onboarding to the new service.

* Deleting fabricbot.json

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

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