rpk: bootstrap and init to use file or default

we want that every write path of rpk use only what
is in the file or the default if there is no file
on disk.

src/go/rpk/pkg/cli/cmd/redpanda/config.go

@@ -105,6 +105,7 @@ func bootstrap(fs afero.Fs) *cobra.Command {
 			p := config.ParamsFromCommand(cmd)
 			cfg, err := p.Load(fs)
 			out.MaybeDie(err, "unable to load config: %v", err)
+			cfg = cfg.FileOrDefaults()
 
 			seeds, err := parseSeedIPs(ips)
 			out.MaybeDieErr(err)
@@ -168,6 +169,7 @@ func initNode(fs afero.Fs) *cobra.Command {
 			p := config.ParamsFromCommand(cmd)
 			cfg, err := p.Load(fs)
 			out.MaybeDie(err, "unable to load config: %v", err)
+			cfg = cfg.FileOrDefaults()
 
 			// Don't reset the node's UUID if it has already been set.
 			if cfg.NodeUUID == "" {