[minishift] CentOS CI has 8 executors now means 8 parallel jobs

Hi All, I am very glad to inform that we got 8 executors for CentOS CI which is doubled than our previous 4 executors. We definitely can think of having the parallelism of jobs for running our time-consuming integration tests (30mins+). Let's discuss the strategy in the issue https://github.com/ minishift/minishift/issues/1396. Regards, Budh Ram Gurung Software Engineer - Devtools