Prepares identity release 1.19.0-beta.1 (#47286)

* Prepares identity release 1.19.0-beta.1

* Changelog update

Author: anannya03

sdk/identity/azure-identity/CHANGELOG.md

@@ -1,15 +1,12 @@
 # Release History
 
-## 1.19.0-beta.1 (Unreleased)
+## 1.19.0-beta.1 (2025-11-14)
 
 ### Features Added
 - Added `enableAzureTokenProxy()` method to `WorkloadIdentityCredentialBuilder` to enable custom token proxy support for Azure Kubernetes clusters. When enabled, the credential attempts to use a custom token proxy configured through environment variables (`AZURE_KUBERNETES_TOKEN_PROXY`, `AZURE_KUBERNETES_CA_FILE`, `AZURE_KUBERNETES_CA_DATA`, `AZURE_KUBERNETES_SNI_NAME`).
 
-### Breaking Changes
-
-### Bugs Fixed
-
 ### Other Changes
+- Ported the authentication flow of WorkloadIdentityCredential to use Msal4j.
 
 ## 1.18.1 (2025-10-13)