[ISSUE] Unset the network connectivity configuration for the Azure databricks workspace.

[krupakar1329]

Problem Statement Once the network connectivity configuration (NCC) is updated for a Databricks workspace, there is currently no way to disable or unset this configuration. This limitation can be restrictive in scenarios where the network configuration needs to be reverted or removed due to changes in network policies, troubleshooting needs, or other administrative reasons.https://docs.databricks.com/api/azure/account/workspaces/update

Proposed Solution Introduce an enhancement to the existing API endpoint for updating the workspace configuration that allows unsetting the network connectivity configuration.

Additional Context

• Allow the network_connectivity_config_id field in the request body to accept a null value.
• When network_connectivity_config_id is set to null, the existing network connectivity configuration should be removed from the workspace

Example Example Use Case: An administrator initially sets up a specific network connectivity configuration for a workspace for a particular project. Once the project is completed, the administrator wants to remove the custom network configuration and revert the workspace to its default state. This feature will allow the administrator to easily unset the network configuration without having to delete and recreate the workspace.