Always use $wgCentralDBname in wfGetDB

It seems the code expected it would only
apparently be run on metawiki, but this is so
not the case....

2013-03-09 01:21:30 mw1138 enwiki: #0 /usr/local/apache/common-local/php-1.21wmf10/includes/db/Database.php(984): DatabaseBase->reportQueryError('Table 'enwiki.c...', 1146, 'SELECT  *  FROM...', 'Campaign::campa...', false)
1 /usr/local/apache/common-local/php-1.21wmf10/includes/db/Database.php(1435): DatabaseBase->query('SELECT  *  FROM...', 'Campaign::campa...')
2 /usr/local/apache/common-local/php-1.21wmf10/extensions/CentralNotice/includes/Campaign.php(769): DatabaseBase->select('cn_notice_log', '*', Array, 'Campaign::campa...', Array)
3 /usr/local/apache/common-local/php-1.21wmf10/extensions/CentralNotice/api/ApiCentralNoticeLogs.php(22): Campaign::campaignLogs(NULL, NULL, NULL, NULL, 50, 0)
4 /usr/local/apache/common-local/php-1.21wmf10/includes/api/ApiQuery.php(302): ApiCentralNoticeLogs->execute()
5 /usr/local/apache/common-local/php-1.21wmf10/includes/api/ApiMain.php(833): ApiQuery->execute()
6 /usr/local/apache/common-local/php-1.21wmf10/includes/api/ApiMain.php(373): ApiMain->executeAction()
7 /usr/local/apache/common-local/php-1.21wmf10/includes/api/ApiMain.php(350): ApiMain->executeActionWithErrorHandling()
8 /usr/local/apache/common-local/php-1.21wmf10/api.php(77): ApiMain->execute()
9 /usr/local/apache/common-local/live-1.5/api.php(3): require('/usr/local/apac...')
10 {main}
Sat Mar 9 1:21:30 UTC 2013      mw1138  enwiki  Campaign::campaignLogs  10.64.16.6      1146    Table 'enwiki.cn_notice_log' doesn't exist (10.64.16.6) SELECT  *  FROM `cn_notice_log`   ORDER BY notlog_timestamp DESC LIMIT 50

Change-Id: I5de9d1f66838094472a8268ef1678f9709aa9eb5