network-legacy/ifup: nuke pid and lease files if dhclient failed
    
    Otherwise we won't retry dhclient again on that interface. In
    FCOS/RHCOS, we want to bake in `ip=dhcp,dhcp6` so we automatically try
    getting a DHCPv6 lease if DHCPv4 failed.
    
    Related: https://bugzilla.redhat.com/show_bug.cgi?id=1793591
    (cherry picked from commit d0de58f23252a9da4a8badd71777e7c8418fa4b7)
    
    patch_name: 0063.patch
    present_in_specfile: true
    location_in_specfile: 63
    squash_commits: true