azure subnet update remove service-endpoints

[anattapol]

az feedback auto-generates most of the information requested below, as of CLI version 2.0.62

Describe the bug
Existing service endpoints were removed if we run the commands without mention every service endpoints.
The blow command will remove all service endpoints in the subnet mention and add only service-endpoint mentions in the command.

az network vnet subnet update -n $subnet_name -g $network_rg_name --vnet-name $vnet --subscription $subscription_id --service-endpoints Microsoft.ContainerRegistry

To Reproduce

1. Select vnet
2. Create service endpoint e.g. cosmos DB and select the subnet
3. Run the command to enable another services endpoints e.g. ContainerRegistry

az network vnet subnet update -n $subnet_name -g $network_rg_name --vnet-name $vnet --subscription $subscription_id --service-endpoints Microsoft.ContainerRegistry

4. Existing Service endpoint (Cosmos DB) was deleted.

Expected behavior
Existing service endpoints should not be deleted.

Environment summary
azure cli
virtual network
service endpoint
OSX

[yonzhan]

network