Improve error message + button when an error occurred during subwiki provisioning

Right now it says "The wiki playground has been created but some pages have not been installed. In consequence, the wiki might behave erroneously and you should probably delete it."

However I had all the pages saved fine. But I had some errors in the logs because (for example) the solr server was not accessible. In practice this didn't affect the provisioning.

The message should simply mention that there were some errors in the logs, asking the user to review them.

Then we should offer 2 choices: delete the created wiki or continue with it.