nixos/jenkins-job-builder: set serviceConfig.Type = "oneshot"

This change allows detecting configuration errors during
switch-to-configuration instead of them being reported asynchronously
*after* switch-to-configuration has exited.

(And update the NixOS test accordingly.)

nixos/modules/services/continuous-integration/jenkins/job-builder.nix

@@ -243,6 +243,7 @@ in {
             done
           '' + (if cfg.accessUser != "" then reloadScript else "");
       serviceConfig = {
+        Type = "oneshot";
         User = jenkinsCfg.user;
         RuntimeDirectory = "jenkins-job-builder";
       };

nixos/tests/jenkins.nix

@@ -81,7 +81,7 @@ import ./make-test-python.nix ({ pkgs, ...} : {
     in ''
     start_all()
 
-    master.wait_for_unit("jenkins")
+    master.wait_for_unit("default.target")
 
     assert "Authentication required" in master.succeed("curl http://localhost:8080")
 
@@ -96,8 +96,6 @@ import ./make-test-python.nix ({ pkgs, ...} : {
 
     with subtest("jobs are declarative"):
         # Check that jobs are created on disk.
-        master.wait_for_unit("jenkins-job-builder")
-        master.wait_until_fails("systemctl is-active jenkins-job-builder")
         master.wait_until_succeeds("test -f /var/lib/jenkins/jobs/job-1/config.xml")
         master.wait_until_succeeds("test -f /var/lib/jenkins/jobs/folder-1/config.xml")
         master.wait_until_succeeds("test -f /var/lib/jenkins/jobs/folder-1/jobs/job-2/config.xml")
@@ -115,8 +113,6 @@ import ./make-test-python.nix ({ pkgs, ...} : {
         )
 
         # Check that jobs are removed from disk.
-        master.wait_for_unit("jenkins-job-builder")
-        master.wait_until_fails("systemctl is-active jenkins-job-builder")
         master.wait_until_fails("test -f /var/lib/jenkins/jobs/job-1/config.xml")
         master.wait_until_fails("test -f /var/lib/jenkins/jobs/folder-1/config.xml")
         master.wait_until_fails("test -f /var/lib/jenkins/jobs/folder-1/jobs/job-2/config.xml")