Configure nodes.conf path dynamically from config

Removes the use of init() to initialize the variable.

- Closes: #1596
- See also: #1569

Signed-off-by: Jonathon Anderson <janderson@ciq.com>

internal/app/wwctl/upgrade/cobra.go

@@ -7,17 +7,15 @@ import (
 	"github.com/warewulf/warewulf/internal/app/wwctl/upgrade/nodes"
 )
 
-var (
-	Command = &cobra.Command{
+func GetCommand() *cobra.Command {
+	command := &cobra.Command{
 		DisableFlagsInUseLine: true,
 		Use:                   "upgrade <config|nodes> [OPTIONS]",
 		Short:                 "Upgrade configuration files",
 		Long: `Upgrade warewulf.conf or nodes.conf from a previous version of Warewulf 4 to a format
 supported by the current version.`,
 	}
-)
-
-func init() {
-	Command.AddCommand(config.Command)
-	Command.AddCommand(nodes.Command)
+	command.AddCommand(config.GetCommand())
+	command.AddCommand(nodes.GetCommand())
+	return command
 }