This change corrects a few logging issues:
* Standardized formatting errors with '%v'.
* Standardized failure warning word usage.
* Corrected an instance of using the standard log library when
the gitea log library should be used instead.
* Remove the default console logger when it is not set in the configuration
* Added comment to new function (lint failure)
* update based on PR comments (code style)
* code style fix (thanks bkcsoft)
* check if logger exists based on the l.outputs (like in l.DelLogger) instead of adapter, otherwise panic when reinstalling gitea (since the output adapter still exist, without outputs)