ci(bstein-home): use mounted harbor auth config

Jenkinsfile

@@ -175,7 +175,6 @@ PY
     stage('Prep toolchain') {
       steps {
         container('builder') {
-          withCredentials([usernamePassword(credentialsId: 'harbor-robot', usernameVariable: 'HARBOR_USERNAME', passwordVariable: 'HARBOR_PASSWORD')]) {
           sh '''
             set -euo pipefail
             for attempt in 1 2 3 4 5; do
@@ -189,12 +188,11 @@ PY
               sleep $((attempt * 2))
             done
             mkdir -p /root/.docker
-              printf '%s' "${HARBOR_PASSWORD}" | docker login registry.bstein.dev -u "${HARBOR_USERNAME}" --password-stdin
+            cp /docker-config/config.json /root/.docker/config.json
           '''
         }
       }
     }
-    }
 
     stage('Compute version') {
       steps {