etcd: client: str: We do not want the prefix match

This was a likely copy+pasta error, since we match precise strings here.
If we had two similarly prefixed strings, we'd have an error.

etcd/client/str/str.go

@@ -62,7 +62,7 @@ func WatchStr(ctx context.Context, client interfaces.Client, key string) (chan e
 func GetStr(ctx context.Context, client interfaces.Client, key string) (string, error) {
 	// new key structure is $NS/strings/$key = $data
 	path := fmt.Sprintf("%s/strings/%s", ns, key)
-	keyMap, err := client.Get(ctx, path, etcd.WithPrefix())
+	keyMap, err := client.Get(ctx, path)
 	if err != nil {
 		return "", errwrap.Wrapf(err, "could not get strings in: %s", key)
 	}