Fix issue related to subscription selection during installation

[santhoshb-msft]

Is your feature request related to a problem? Please describe.
Fix issue related to subscription selection during installation

Describe the solution you'd like
Two things

1. Fail when there is an error on this line
   az account set -s $AzureSubscriptionID
2. Should the selected sub through az account instead of the variable name
   Write-Host "🔑 Azure Subscription '$AzureSubscriptionID' selected."

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.