Sets wgBlockDisablesLogin true on private wikis.

This change will affect the following wikis:
	- arbcom_enwiki
	- arbcom_fiwiki
	- boardgovcomwiki
	- grantswiki
	- iegcomwiki
	- ilwikimedia
	- movementroleswiki
	- searchcomwiki
	- spcomwiki
	- transitionteamwiki
	- wg_enwiki

On other private wikis, this setting is already enabled.

Bug: 53871
Change-Id: I37b9b5210a207faa26393221047bc766c4844f7c