kie-issues#1237: stay on x.y.999-SNAPSHOT in release branches (#3527)

Co-authored-by: jstastny-cz <jan.stastny@ibm.com>

.ci/jenkins/Jenkinsfile.setup-branch

@@ -53,7 +53,7 @@ pipeline {
                         currentBuild.displayName = params.DISPLAY_NAME
                     }
 
-                    checkoutRepo(droolsRepo, getDroolsTargetBranch())
+                    checkoutRepo(droolsRepo, getBuildBranch())
                     checkoutRepo(getRepoName(), getBuildBranch())
                 }
             }
@@ -151,18 +151,6 @@ void checkoutRepo(String repository, String branch) {
     }
 }
 
-String getDroolsTargetBranch() {
-    String targetBranch = getBuildBranch()
-    List versionSplit = targetBranch.split("\\.") as List
-
-    if (versionSplit[0].isNumber()) {
-        targetBranch = "${Integer.parseInt(versionSplit[0]) + 7}.${versionSplit.tail().join('.')}"
-    } else {
-        echo "Cannot parse targetBranch as release branch so going further with current value: ${targetBranch}"
-    }
-    return targetBranch
-}
-
 String getRepoName() {
     return env.REPO_NAME
 }