remove alerts brownfield and update readme with relocated info to AMBA

[JCoreMS]

Overview/Summary

Removed the Brownfield code for AVD Alerts to include ARM and BICEP files as well as the UI definition and Scripts. Updated readme to denote the relocation to AMBA with the associated link/ URL.

This PR fixes/adds/changes/removes

N/A

Breaking Changes

N/A

Testing Evidence

N/A

As part of this Pull Request I have

• [X] Read the Contribution Guide and ensured this PR is compliant with the guide
• [X] Ensured the resource API versions in .bicep file/s I am adding/editing are using the latest API version possible
• [X] Checked for duplicate Pull Requests
• [X] Associated it with relevant GitHub Issues
• [X] (AVD LZA Team Only) Associated it with relevant ADO Items
• [X] Ensured my code/branch is up-to-date with the latest changes in the main branch
• [X] Performed testing and provided evidence.
• [X] Updated relevant and associated documentation (e.g. Contribution Guide, Module READMEs, Docs etc.)