MT#19571 Remove {kamailio}{lb}{children} option from config_debug.pl as it doesn't exist

Having it here affects further ngcp-ngcpcfg-check Jenkins test which reports:

> 2016-05-06 02:23:46: Error: Invalid schema detected for /etc/ngcp-config/config.yml
> /etc/ngcp-config/config.yml#0: INVALID
>   - [/kamailio/lb/children] Unexpected key 'children'

It happen only in case if kamailio-config-tests Jenkins job failed
and it didn't cleanup/restore original config.

Change-Id: I48eef343c3a1813af6e18b0d0b426d539dc2950b

bin/config_debug.pl

@@ -93,7 +93,6 @@ else
 {
   copy($file, $file.".orig") or die "Copy failed: $ERRNO" unless(-e $file.".orig");
   $yaml = LoadFile($file) or die "File $file could not be read";
-  $yaml->{kamailio}{lb}{children} = 1;
   $yaml->{kamailio}{lb}{debug} = 'yes';
   $yaml->{kamailio}{lb}{use_dns_cache} = 'off';
   $yaml->{kamailio}{proxy}{children} = 1;