Do not list active repositories as unadopted (#22034)

This fixes a bug where, when searching unadopted repositories, active
repositories will be listed as well. This is because the size of the
array of repository names to check is larger by one than the
`IterateBufferSize`.

For an `IterateBufferSize` of 50, the original code will pass 51
repository names but set the query to `LIMIT 50`. If all repositories in
the query are active (i.e. not unadopted) one of them will be omitted
from the result. Due to the `ORDER BY` clause it will be the oldest (or
least recently modified) one.

Bug found in 1.17.3.

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

services/repository/adopt.go

@@ -337,7 +337,7 @@ func ListUnadoptedRepositories(query string, opts *db.ListOptions) ([]string, in
 		}
 
 		repoNamesToCheck = append(repoNamesToCheck, name)
-		if len(repoNamesToCheck) > setting.Database.IterateBufferSize {
+		if len(repoNamesToCheck) >= setting.Database.IterateBufferSize {
 			if err = checkUnadoptedRepositories(userName, repoNamesToCheck, unadopted); err != nil {
 				return err
 			}