Switch file log level to info

Reduces multi-GB log files. Main culprits were:

- [upload.go:385] could not find cache entry for...
- [content_manager.go:790] WriteContent("...") - new
- [content_manager.go:396] adding ... length=... deleted=false
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f