backport of commit 425b1e333d (#23885)

Co-authored-by: Josh Black <raskchanky@gmail.com>

changelog/23872.txt

@@ -0,0 +1,3 @@
+```release-note:improvement
+storage/etcd: etcd should only return keys when calling List()
+```

physical/etcd/etcd3.go

@@ -14,7 +14,7 @@ import (
 	"sync"
 	"time"
 
-	metrics "github.com/armon/go-metrics"
+	"github.com/armon/go-metrics"
 	log "github.com/hashicorp/go-hclog"
 	"github.com/hashicorp/go-secure-stdlib/parseutil"
 	"github.com/hashicorp/go-secure-stdlib/strutil"
@@ -238,7 +238,7 @@ func (c *EtcdBackend) List(ctx context.Context, prefix string) ([]string, error)
 	ctx, cancel := context.WithTimeout(context.Background(), c.requestTimeout)
 	defer cancel()
 	prefix = path.Join(c.path, prefix) + "/"
-	resp, err := c.etcd.Get(ctx, prefix, clientv3.WithPrefix())
+	resp, err := c.etcd.Get(ctx, prefix, clientv3.WithPrefix(), clientv3.WithKeysOnly())
 	if err != nil {
 		return nil, err
 	}

physical/etcd/etcd3_test.go

@@ -26,7 +26,7 @@ func TestEtcd3Backend(t *testing.T) {
 		"username": "root",
 		"password": "insecure",
 
-		// Syncing adverticed client urls should be disabled since docker port mapping confuses the client.
+		// Syncing advertised client urls should be disabled since docker port mapping confuses the client.
 		"sync": "false",
 	}