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() // we modify fields in the raw file without writing env / flag overrides
 
 			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() // we modify fields in the raw file without writing env / flag overrides
 
 			// Don't reset the node's UUID if it has already been set.
 			if cfg.NodeUUID == "" {