getFirstMinion should return minion id

* Minion id may not be in FQDN format
* pipeline-library should not use any wildcards (*) for minion
  targeting
* Unexpected minions may be filtered for result of this function
  For example:
    getFirstMinion returns 'ctl01'
    execution of salt.getReturnValues with 'ctl01*' will also filter
    'ctl0100'

Change-Id: Ia2b3460aeabc928f7cfa7d01a4dacb91e36c9e9d
Related-PROD: PROD-22709
2 files changed