Use globals instead of WikiFactory::getVarValueByName when on a local wiki
BAC-150: AutoCreateWiki cleanup

* remove old Special:CreateWiki (redirect to Special:CreateNewWiki is handled by the current code)
* remove templates and JS
* remove AJAX functions
BAC-150: remove more assets
BAC-150: remove not used constant
Revert "Use globals instead of WikiFactory::getVarValueByName when on a local wiki"

This reverts commit 386dce0dcda6e94ba58cd140fef8ba4aabb45902.
BAC-150: CreateWiki cleanup
Merge pull request #734 from Wikia/bac-150-awc-cleanup

BAC-150: AutoCreateWiki cleanup