[skip ci] update nightly cron (#2680)

* Change Milvus Helm Version to v0.10.1
Signed-off-by: Nquicksilver <zhifeng.zhang@zilliz.com>

* [skip ci] update nightly cron
Signed-off-by: Nquicksilver <zhifeng.zhang@zilliz.com>

ci/jenkins/Jenkinsfile

 #!/usr/bin/env groovy
 
 String cron_timezone = "TZ=Asia/Shanghai"
-String cron_string = BRANCH_NAME == "0.10.1" ? "30 14 * * * " : ""
+String cron_string = BRANCH_NAME == "0.10.1" ? "50 22 * * * " : ""
 
 pipeline {
     agent none

ci/jenkins/step/singleDevNightlyTest.groovy

@@ -32,7 +32,7 @@ timeout(time: 180, unit: 'MINUTES') {
     // sqlite database backend test
     load "ci/jenkins/step/cleanupSingleDev.groovy"
     
-    if (!fileExists('milvus-helm')) {
+    if (!fileExists('milvus-helm/charts/milvus')) {
         dir ("milvus-helm") {
             checkout([$class: 'GitSCM', branches: [[name:"${env.HELM_BRANCH}"]], userRemoteConfigs: [[url: "https://github.com/milvus-io/milvus-helm.git", name: 'origin', refspec: "+refs/heads/${env.HELM_BRANCH}:refs/remotes/origin/${env.HELM_BRANCH}"]]])
         }