use an ubuntu agent to build binaries for MacOSX unit tests

Author: g7ed6e

azure-pipelines-arcade.yml

@@ -228,7 +228,7 @@ stages:
           timeoutInMinutes: 90
           pool:
             name: NetCore-Public
-            demands: ImageOverride -equals windows.vs2022.amd64.open
+            demands: ImageOverride -equals build.Ubuntu.1804.amd64.open
           variables:
           - _TestArgs: /p:ServiceUri=$(_serviceUri) /p:Root_Certificate_Installed=true /p:Client_Certificate_Installed=true /p:SSL_Available=true
           - _serviceUri: wcfcoresrv23.westus3.cloudapp.azure.com/WcfService$(_WcfPRServiceId)