Remove cron override code for VIP Go

[mjangda]

In #131, we restored the cron builder for VIP Go sites, but did not remove the related overrides, which means that we end up creating multiple events for each day which do the same thing; e.g.

| msm_cron_generate_sitemap_for_year_month           |           4 |
| msm_cron_generate_sitemap_for_year_month_day       |        5821 |
| msm_cron_update_sitemap                            |           1 |
| msm_vipgo_cron_generate_sitemap_for_year_month_day |        1183 |

[davidsword]

Is there anything holding this back from being merged in? Is any additional testing needed?

[mdbitz]

Approved :) As discussed these are extra events duplicating functionality that should have been removed in #131