Delete AzureApplicationCredential API in Azure Identity library (Azure#50624)

* Delete AzureApplicationCredential

* Delete files

Author: scottaddie

sdk/identity/Azure.Identity/CHANGELOG.md

@@ -11,7 +11,9 @@
 - `ManagedIdentityCredential` throws `CredentialUnavailableException` when the IMDS endpoint is unavailable. This addresses a regression in how it behaves in the `ChainedTokenCredential` ([47057](https://github.com/Azure/azure-sdk-for-net/issues/47057)).
 
 ### Other Changes
+
 - `VisualStudioCredential` throws `CredentialUnavailableException` for all failures except for OperationCancelledException due to cancellation being requested for a `CancellationToken`. This ensures that it falls through for most failures when part of a chained credential.
+- Removed `AzureApplicationCredential`. For context, see issue [49781](https://github.com/Azure/azure-sdk-for-net/issues/49781).
 
 ## 1.14.0 (2025-05-13)