Suspend Crowd2 plugin distribution - uses closed source dependency

jenkins-infra/helpdesk#3854 explains that
the Crowd2 integration plugin uses a dependency that is not open source
licensed.

The Crowd2 integration library is Atlassian licensed as described in
jenkins-infra/helpdesk#3842 (comment)

The Atlassian license is not an open source license.  Refer to
https://www.atlassian.com/legal/software-license-agreement for the
details of the license.

https://www.jenkins.io/project/governance/#license says that the Jenkins
project requires plugins that it distributes to be open source, including
their dependencies.  When a closed source dependency is detected in a
plugin, we suspend distribution of that plugin.  If maintainers update
the plugin to remove the closed source dependency, distribution can
begin for the new release that removes the closed source dependency.

Fixes jenkins-infra/helpdesk#3854

resources/artifact-ignores.properties

@@ -402,7 +402,6 @@ [email protected]              # While we serve pre-2.7 update sites; depends on
 # depends on scripttrigger
 xtrigger = https://www.jenkins.io/security/plugins/#suspensions
 
-
 # These plugins implement Groovy scripting in an unsafe way, but are currently unreleased -- so suspend preemptively
 groovy-choice-parameter
 groovy-script-scheduler
@@ -887,3 +886,11 @@ [email protected]               # SECURITY-1025
 [email protected]               # SECURITY-1025
 [email protected]               # SECURITY-1025
 [email protected]               # SECURITY-1025
+
+# Non-open dependency, refer to:
+#   https://github.com/jenkins-infra/helpdesk/issues/3854
+#   https://github.com/jenkins-infra/helpdesk/issues/3842#issuecomment-1839385370
+#   https://github.com/jenkins-infra/helpdesk/issues/3842#issuecomment-1841569022
+#   https://github.com/jenkins-infra/helpdesk/issues/3842#issuecomment-1847399101
+#   https://github.com/jenkins-infra/helpdesk/issues/3842#issuecomment-1847559631
+crowd2 = https://github.com/jenkins-infra/helpdesk/issues/3854