ci: shorten PostgreSQL smoke socket path

Jenkinsfile

@@ -26,7 +26,8 @@ pipeline {
         DOTNET_CLI_HOME = "${WORKSPACE}/.ci/dotnet-home"
         POSTGRES_SERVICE_BUILD_TMPDIR = "${WORKSPACE}/.ci/fnos-build"
         LIVERECORDER_VERIFY_TMPDIR = "${WORKSPACE}/.ci/fnos-verify"
-        POSTGRES_SERVICE_SMOKE_TMPDIR = "${WORKSPACE}/.ci/fnos-smoke"
+        # Keep PostgreSQL's Unix-domain socket below Linux's 107-byte path limit.
+        POSTGRES_SERVICE_SMOKE_TMPDIR = "/tmp/postgresshare-smoke-${BUILD_NUMBER}"
     }
 
     stages {
@@ -124,6 +125,9 @@ PY
 
     post {
         success { archiveArtifacts artifacts: 'artifacts/*.fpk,artifacts/*.sha256,artifacts/*.json', fingerprint: true }
-        always { cleanWs(deleteDirs: true, notFailBuild: true) }
+        always {
+            sh 'rm -rf -- "$POSTGRES_SERVICE_SMOKE_TMPDIR"'
+            cleanWs(deleteDirs: true, notFailBuild: true)
+        }
     }
 }