Update Created by tag logic

Author: NirajC-Microsoft

infra/main.bicep

@@ -223,8 +223,8 @@ var allTags = union(
   },
   tags
 )
-@description('Optional created by user name')
-param createdBy string = empty(deployer().userPrincipalName) ? '' : split(deployer().userPrincipalName, '@')[0] 
+@description('Tag, Created by user name')
+param createdBy string = contains(deployer(), 'userPrincipalName')? split(deployer().userPrincipalName, '@')[0]: deployer().objectId
 
 resource resourceGroupTags 'Microsoft.Resources/tags@2021-04-01' = {
   name: 'default'