Update federation target to etcd/clientv3 (#6119)

With CoreDNS now supporting etcdv3 as the DNS backend, we
can update our federation target to etcdv3. Users will now be
able to use etcdv3 server as the federation backbone.

Minio will update bucket data to etcdv3 and CoreDNS can pick
that data up and serve it as bucket style DNS path.

vendor/golang.org/x/net/context/pre_go17.go

@@ -13,7 +13,7 @@ import (
 	"time"
 )
 
-// An emptyCtx is never canceled, has no values, and has no deadline.  It is not
+// An emptyCtx is never canceled, has no values, and has no deadline. It is not
 // struct{}, since vars of this type must have distinct addresses.
 type emptyCtx int
 
@@ -104,7 +104,7 @@ func propagateCancel(parent Context, child canceler) {
 }
 
 // parentCancelCtx follows a chain of parent references until it finds a
-// *cancelCtx.  This function understands how each of the concrete types in this
+// *cancelCtx. This function understands how each of the concrete types in this
 // package represents its parent.
 func parentCancelCtx(parent Context) (*cancelCtx, bool) {
 	for {
@@ -134,14 +134,14 @@ func removeChild(parent Context, child canceler) {
 	p.mu.Unlock()
 }
 
-// A canceler is a context type that can be canceled directly.  The
+// A canceler is a context type that can be canceled directly. The
 // implementations are *cancelCtx and *timerCtx.
 type canceler interface {
 	cancel(removeFromParent bool, err error)
 	Done() <-chan struct{}
 }
 
-// A cancelCtx can be canceled.  When canceled, it also cancels any children
+// A cancelCtx can be canceled. When canceled, it also cancels any children
 // that implement canceler.
 type cancelCtx struct {
 	Context
@@ -193,8 +193,8 @@ func (c *cancelCtx) cancel(removeFromParent bool, err error) {
 }
 
 // WithDeadline returns a copy of the parent context with the deadline adjusted
-// to be no later than d.  If the parent's deadline is already earlier than d,
-// WithDeadline(parent, d) is semantically equivalent to parent.  The returned
+// to be no later than d. If the parent's deadline is already earlier than d,
+// WithDeadline(parent, d) is semantically equivalent to parent. The returned
 // context's Done channel is closed when the deadline expires, when the returned
 // cancel function is called, or when the parent context's Done channel is
 // closed, whichever happens first.
@@ -226,8 +226,8 @@ func WithDeadline(parent Context, deadline time.Time) (Context, CancelFunc) {
 	return c, func() { c.cancel(true, Canceled) }
 }
 
-// A timerCtx carries a timer and a deadline.  It embeds a cancelCtx to
-// implement Done and Err.  It implements cancel by stopping its timer then
+// A timerCtx carries a timer and a deadline. It embeds a cancelCtx to
+// implement Done and Err. It implements cancel by stopping its timer then
 // delegating to cancelCtx.cancel.
 type timerCtx struct {
 	*cancelCtx
@@ -281,7 +281,7 @@ func WithValue(parent Context, key interface{}, val interface{}) Context {
 	return &valueCtx{parent, key, val}
 }
 
-// A valueCtx carries a key-value pair.  It implements Value for that key and
+// A valueCtx carries a key-value pair. It implements Value for that key and
 // delegates all other calls to the embedded Context.
 type valueCtx struct {
 	Context