jobs/kola-*: trim artifacts to 30

Keeping around the test console logs of the last 100 builds seems
excessive. Let's trim it back to 30 to match bump-lockfile. This should
help reduce our storage requirements (each kola job right now takes
about 1.2G- 1.4G).

Author: jlebon

jobs/kola-aws.Jenkinsfile

@@ -34,7 +34,7 @@ properties([
     ]),
     buildDiscarder(logRotator(
         numToKeepStr: '100',
-        artifactNumToKeepStr: '100'
+        artifactNumToKeepStr: '30'
     )),
     durabilityHint('PERFORMANCE_OPTIMIZED')
 ])

jobs/kola-azure.Jenkinsfile

@@ -34,7 +34,7 @@ properties([
     ]),
     buildDiscarder(logRotator(
         numToKeepStr: '100',
-        artifactNumToKeepStr: '100'
+        artifactNumToKeepStr: '30'
     )),
     durabilityHint('PERFORMANCE_OPTIMIZED')
 ])

jobs/kola-gcp.Jenkinsfile

@@ -34,7 +34,7 @@ properties([
     ]),
     buildDiscarder(logRotator(
         numToKeepStr: '100',
-        artifactNumToKeepStr: '100'
+        artifactNumToKeepStr: '30'
     )),
     durabilityHint('PERFORMANCE_OPTIMIZED')
 ])

jobs/kola-openstack.Jenkinsfile

@@ -34,7 +34,7 @@ properties([
     ]),
     buildDiscarder(logRotator(
         numToKeepStr: '100',
-        artifactNumToKeepStr: '100'
+        artifactNumToKeepStr: '30'
     )),
     durabilityHint('PERFORMANCE_OPTIMIZED')
 ])