Customization files should not require /assets path segment

[silverwind]

Since #15219, previous customization files like $GITEA_CUSTOM/public/img/logo.svg are not loaded any more and require $GITEA_CUSTOM/public/assets/img/logo.svg to be loaded again, we should fix this because the assets segment should only be relevant on HTTP, not in the file system.

[silverwind]

@a1012112796 fyi.

[lunny]

I think this has been resolved by #15961 .

[silverwind]

Yeah, just rebuilt with that, seems to have been resolved.