Only use DefaultAzureCredential for local debug

[japarson]

DefaultAzureCredential offers a balanced approach to retries, response wait times, and multiple authentication mechanisms. However, production workloads require resilience to latencies, robust retries, and deterministic behavior. Using DefaultAzureCredential() in Azure production services can lead to additional IcMs during managed identity service (IMDS) outages. During such outages, DefaultAzureCredential continues to probe additional credentials after ManagedIdentityCredential times out, including development-time credentials such as AzureCliCredential, AzureDeveloperCliCredential, and AzurePowerShellCredential. This behavior causes your service to be flagged by AzSecPack for suspicious activity.

We should avoid using DefaultAzureCredential in any context except for debug builds which can be used to more easily authenticate when developing locally.

Addresses https://github.com/NuGet/Engineering/issues/5869

[etvorun]

How hard would it be to use IAppConfiguration.Environment == ServicesConstants.DevelopmentEnvironment? The idea is to avoid use #if DEBUG. In all the new places