[release/9.0] Pass container image correctly for source-build job in official build

Backport of #64770

Author: akoeplinger

.azure/pipelines/ci.yml

@@ -708,7 +708,7 @@ extends:
           enableInternalSources: true
           platform:
             name: 'Managed'
-            container: 'mcr.microsoft.com/dotnet-buildtools/prereqs:centos-stream8'
+            container: azureLinux30Net9BuildAmd64
             buildScript: './eng/build.sh --publish --no-build-repo-tasks $(_PublishArgs) $(_InternalRuntimeDownloadArgs)'
             skipPublishValidation: true
             jobProperties: