docker registry delete download counts on push

[6543]

if you push a docker image to same existing tag, download counts are erased.

to reproduce:

1. push a docker image with tag :latest
2. delete image local and download image -> download count shows 1
3. push a new image with tag :latest
4. download count is 0 again

gitea version: v1.17.0 - main

[6543]

@KN4CK3R is this intended?

[KN4CK3R]

No, fixed in #20728