commands: Remove the benchmark command

It's not particulary useful, and when we start to get bug reports about it, it is easier to remove it.

Closes #5543

commands/commands.go

@@ -48,7 +48,6 @@ func (b *commandsBuilder) addAll() *commandsBuilder {
 		newEnvCmd(),
 		newConfigCmd(),
 		newCheckCmd(),
-		b.newBenchmarkCmd(),
 		newConvertCmd(),
 		b.newNewCmd(),
 		newListCmd(),