cmd/geth: set EnableBashCompletion = true (#24313)

prepare #24145

internal/flags/helpers.go

@@ -143,6 +143,7 @@ func FlagCategory(flag cli.Flag, flagGroups []FlagGroup) string {
 // NewApp creates an app with sane defaults.
 func NewApp(gitCommit, gitDate, usage string) *cli.App {
 	app := cli.NewApp()
+	app.EnableBashCompletion = true
 	app.Name = filepath.Base(os.Args[0])
 	app.Author = ""
 	app.Email = ""