Retry three time validation on changes

With more nodes and more builds it may happen
that an executor fails for disconnection with the master.

Retry up to three times the validation of change before
declaring the build as failed.

Change-Id: If040a3a8ccf969af4b9a49e87271064ec09b78b4
diff --git a/jenkins/gerrit-verifier-change.groovy b/jenkins/gerrit-verifier-change.groovy
index 1ff463c..f4a1960 100644
--- a/jenkins/gerrit-verifier-change.groovy
+++ b/jenkins/gerrit-verifier-change.groovy
@@ -334,7 +334,7 @@
   def builds = []
   println "Running validation jobs using $tools builds for $modes ..."
   modes.collect {
-    prepareBuildsForMode(refspec,sha1,changeUrl,it,tools,branch,1,Globals.codeStyleBranches.contains(branch))
+    prepareBuildsForMode(refspec,sha1,changeUrl,it,tools,branch,3,Globals.codeStyleBranches.contains(branch))
   }.each { builds += it }
 
   def buildsWithResults = getResultsOfBuildsInParallel(builds)