[#1442] cli/tree: Allow to specify rpc-endpoint with config file

We have several ways to specify the `rpc-endpoint`: with a flag,
with a single config file or multiple files. Before, the `rpc-endpoint`
flag was marked as required. Because `cobra` checked the required flag
presence first, it prevented specifying `rpc-endpoint` with a config file.

Signed-off-by: Aleksey Savchuk <a.savchuk@yadro.com>

cmd/frostfs-cli/modules/tree/list.go

@@ -26,8 +26,6 @@ func initListCmd() {
 	ff := listCmd.Flags()
 	ff.String(commonflags.CIDFlag, "", commonflags.CIDFlagUsage)
 	_ = listCmd.MarkFlagRequired(commonflags.CIDFlag)
-
-	_ = cobra.MarkFlagRequired(ff, commonflags.RPC)
 }
 
 func list(cmd *cobra.Command, _ []string) {