multipath.conf is modified incorrectly when using MultipathdCustomConfigFile parameter

Issue

• MultipathdCustomConfigFile is declared in a template file to deploy a specific multipath.conf file.

• However, multipath.conf is modified wrongly after deploying overcloud.

  <Original multipath.conf>
  blacklist {
      devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
      devnode "^hd[a-z]"
  }
  
  blacklist_exceptions {
      device {
          product "XXXX"
          vendor "XXXX"
      }
  }
  
  <Deployed multipath.conf file on overcloud Compute node>
  blacklist {
  }                    <==================(*) added incorrectly
      devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
      devnode "^hd[a-z]"
  }
  
  blacklist {          <==================(*) Changed to blacklist from blacklist_exceptions
  }                    <==================(*) added incorrectly
      device {
          product "XXXX"
          vendor "XXXX"
      }
  }