[BUG] GetProcessorCount for webjobs service bus extension does not override processor count for flex consumption

[paulbatum]

Library name and version

Microsoft.Azure.WebJobs.Extensions.ServiceBus 5.16.4.0

Describe the bug

Logic that uses the processor count to figure out default value of maxConcurrentCalls needs to special case the flex consumption SKU similar to how it special cases the consumption SKU.

This logic is in the GetProcessorCount helper.

https://github.com/Azure/azure-sdk-for-net/blob/main/sdk/servicebus/Microsoft.Azure.WebJobs.Extensions.ServiceBus/src/Utility.cs#L14

Here is some relevant code from functions host for detecting flex consumption via environment variables:
https://github.com/Azure/azure-functions-host/blob/f58df65944a2eca87c7ce0e837b2141f4b0a95bf/src/WebJobs.Script/Environment/EnvironmentExtensions.cs#L225
https://github.com/Azure/azure-functions-host/blob/f58df65944a2eca87c7ce0e837b2141f4b0a95bf/src/WebJobs.Script/ScriptConstants.cs#L119

Expected behavior

Flex consumption apps default to using maxConcurrentCalls = 16.

Actual behavior

Flex consumption apps default to using maxConcurrentCalls = 64, because the system thinks the processor count is 4.

Reproduction Steps

Deploy a service bus triggered function on flex consumption and observe the concurrency behavior.

[github-actions]

Thank you for your feedback. Tagging and routing to the team member best able to assist.

[paulbatum]

@pragnagopa I think it makes more sense for someone on the functions team to make this fix

[github-actions]

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @EldertGrootenboer @shankarsama.