libnetwork/types: remove unused UUID type

This type was added moved to the types package as part of a refactor
in https://github.com/moby/libnetwork/commit/778e2a72b3c6b739d8a9d430b99c75d6ef35f797
but the introduction of the sandbox API changed the existing API to
weak types (not using a plain string);
https://github.com/moby/libnetwork/commit/9a47be244afb706a919fdafa4daef20d3d1b8510

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

libnetwork/types/types.go

@@ -28,9 +28,6 @@ type EncryptionKey struct {
 	LamportTime uint64
 }
 
-// UUID represents a globally unique ID of various resources like network and endpoint
-type UUID string
-
 // QosPolicy represents a quality of service policy on an endpoint
 type QosPolicy struct {
 	MaxEgressBandwidth uint64