[skip ci] CI nightly open (#4768)

Signed-off-by: shengjun.li <shengjun.li@zilliz.com>

ci/jenkins/Jenkinsfile

 #!/usr/bin/env groovy
 
 String cron_timezone = "TZ=Asia/Shanghai"
-String cron_string = BRANCH_NAME == "1.0.0" ? "50 22 * * * " : ""
+String cron_string = BRANCH_NAME == "1.x" ? "50 22 * * * " : ""
 
 pipeline {
     agent none