migrations: remove dead code in gitea uploader (#18725)
migrations: remove dead code in gitea uploader (#18725)

When migrating, g.issues is a map with all issues created during the
migration. If an issue is not found in g.issues when inserting a
comment or a review, it cannot exist in the database and trying to get
it via GetIssueByIndex() will always fail and return an error.

Signed-off-by: singuliere <1a462a8e0b6ab96b81e2f02f0ff0d35811cc5bce@autistici.org>
go-gitea/gitea,go-gitea/gitea,go-gitea/gitea