CI fails consistently, likely due to credential issue

From internal conversation:

Looks like I found the cause for the weird null reference exception: local authentication was disabled for the event hubs resource in the netheriteci resource group. By manually turning this on I could get those tests to pass. I am still seeing some other tests fail with timeout, but that is likely a different issue.

manually turning on local authentication in the portal is not a great solution since the KPIs will continue to flag and/or automatically disable local authentication for event hubs. To make this more robust, we would need to revise the CI tests so they use managed identity for authentication.

Managed identity is now fully supported by Netherite, so it should be just a matter of setting up the tests correctly. Still, that requires some work.

Locate the CI tests and Event Hubs authentication setup referenced in the issue, then read how those tests currently obtain credentials. Update the test setup to use managed identity rather than local authentication, and verify the CI tests pass without manually enabling local authentication.