Revert "network/netplan: adjust link-local accordingly (#443)" (#448)

This reverts commit 2a9cb58.

google_guest_agent/network/manager/netplan_linux.go

@@ -98,9 +98,6 @@ type netplanEthernet struct {
 	DHCPv6 *bool `yaml:"dhcp6,omitempty"`
 
 	DHCP6Overrides *netplanDHCPOverrides `yaml:"dhcp6-overrides,omitempty"`
-
-	// LinkLocal defines the stack to be used for link local i.e: ipv4, ipv6 etc.
-	LinkLocal []string `yaml:"link-local,omitempty"`
 }
 
 // netplanDHCPOverrides sets the netplan dhcp-overrides configuration.
@@ -374,7 +371,6 @@ func (n *netplan) writeNetplanEthernetDropin(mtuMap map[string]int, interfaces,
 			DHCP4Overrides: &netplanDHCPOverrides{
 				UseDomains: shouldUseDomains(i),
 			},
-			LinkLocal: []string{"ipv4"},
 		}
 
 		if mtu, found := mtuMap[iface]; found {
@@ -386,7 +382,6 @@ func (n *netplan) writeNetplanEthernetDropin(mtuMap map[string]int, interfaces,
 			ne.DHCP6Overrides = &netplanDHCPOverrides{
 				UseDomains: shouldUseDomains(i),
 			}
-			ne.LinkLocal = append(ne.LinkLocal, "ipv6")
 		}
 
 		key := n.ID(iface)