chore: Update deployment guides for Fabric capacity parameters and prerequisites

[Harmanpreet-Microsoft]

Purpose

This pull request updates the deployment and setup documentation for Azure Fabric, focusing on clarifying configuration parameters and improving instructions for enabling Fabric capacity and private endpoints. The changes aim to reduce confusion around parameter usage and deployment steps, especially regarding Fabric capacity provisioning and network isolation.

Key documentation improvements:

Fabric Capacity and Private Endpoint Setup:

• Updated the instructions to use fabricCapacityMode = 'create' and fabricWorkspaceMode = 'create' parameters in infra/main.bicepparam instead of the previous deployToggles.fabricCapacity toggle. This clarifies the correct way to provision Fabric capacity and workspace. [1] [2]
• Added a note explaining that there is no fabricPrivateEndpoint toggle in deployToggles and that the Fabric private endpoint module is available for custom deployments but is not part of the default azd up flow.

Deployment Parameter Table Updates:

• Updated the deployment parameter table to remove obsolete parameters (networkIsolationMode, vmAdminUsername, vmAdminPassword) and add new ones (enableTelemetry, enableDefenderForAI, flagPlatformLandingZone) to better reflect current deployment options.

Network Isolation Documentation:

• Clarified network isolation verification steps by referencing specific toggles (deployToggles.applicationGateway, bastionHost, and jumpVm) instead of the removed networkIsolationMode parameter.

• ...

Does this introduce a breaking change?

• Yes
• No

Golden Path Validation

• I have tested the primary workflows (the "golden path") to ensure they function correctly without errors.

Deployment Validation

• I have validated the deployment process successfully and all services are running as expected with this change.

What to Check

Verify that the following are valid

• ...

Other Information