Gitea has added a STACKTRACE_LEVEL config option to set which log level
will also generate stack traces when logging. We want them for at least
Error and above so set this to Error for now. In particular there seems
to be a commit cache issue which results in errors that having stack
traces for would be helpful to debug.
Change-Id: I0491373ef143dfa753c011d02e3c670c699d2a52
941f746767