eliminate OC_Template::printErrorPage in database classes, fixes #12182
errors are already logged
do not output DB information, and do not set header
Merge pull request #12186 from owncloud/fix-12182

eliminate OC_Template::printErrorPage in database classes, fixes #12182
[tx-robot] updated from transifex
[tx-robot] updated from transifex
Remove unused code

We don't support direct updates from older ownCloud versions except the previous one therefore this code is unused and can be removed.