message: update build status source
diff: # Azure SDK for C++
  -[![Build Status](https://dev.azure.com/azure-sdk/public/_apis/build/status/c/c%20-%20client%20-%20ci?branchName=master)](https://dev.azure.com/azure-sdk/public/_build/latest?definitionId=722&branchName=master)
  +[![Build Status](https://dev.azure.com/azure-sdk/public/_apis/build/status/cpp/cpp%20-%20client%20-%20ci?branchName=master)](https://dev.azure.com/azure-sdk/public/_build/latest?definitionId=1611&branchName=master)
  This repository is for active development of the Azure SDK for C++.
  