Discard built artefacts sooner. No one uses Cassandra artefacts built by Jenkins.

ref:
 - https://lists.apache.org/thread.html/r0dea866e2708d4c6fd7ef8af46c938960631aac13d6822d7abcc5284%40%3Cdev.cassandra.apache.org%3E
 - https://jenkinsci.github.io/job-dsl-plugin/#method/javaposse.jobdsl.dsl.jobs.FreeStyleJob.logRotator
diff --git a/jenkins-dsl/cassandra_job_dsl_seed.groovy b/jenkins-dsl/cassandra_job_dsl_seed.groovy
index bf665bd..c4d72c7 100644
--- a/jenkins-dsl/cassandra_job_dsl_seed.groovy
+++ b/jenkins-dsl/cassandra_job_dsl_seed.groovy
@@ -418,6 +418,7 @@
         label(slaveLabel)
         logRotator {
             numToKeep(50)
+            artifactNumToKeep(3)
         }
         wrappers {
             timeout {