[ci] 最簡單的方式設定一旦 push 就 build

Trigger by push.
重要開發線設定 push 就 build, 將來夾 code 就清楚簡單明確.

Jenkins Site

    (a) Install plugins: [Manage Jenkins] -> [Manage Plugins]

                Jenkins GitLab Plugin:-> GitLab Plugin]

                Jenkins Git Plugin

    (b) Project setting:

                 Git clone access for Jenkins from the GitLab repository

Git-lab Site
    (a) Integrate with other service:
Project -> [Integrations]
    (b) Setup WebHook

                 URL: (from Jenkins gitlab trigger build panel)

                 Secret Token: (from Advanced panel in Jenkins gitlab trigger build panel