Check primary keys for all tables and drop ForeignReference (#21721)

Some dbs require that all tables have primary keys, see
- #16802
- #21086

We can add a test to keep it from being broken again.

Edit:

~Added missing primary key for `ForeignReference`~ Dropped the
`ForeignReference` table to satisfy the check, so it closes #21086.

More context can be found in comments.

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: zeripath <art27@cantab.net>

services/migrations/gitea_uploader.go

@@ -17,7 +17,6 @@ import (
 
 	"code.gitea.io/gitea/models"
 	"code.gitea.io/gitea/models/db"
-	"code.gitea.io/gitea/models/foreignreference"
 	issues_model "code.gitea.io/gitea/models/issues"
 	repo_model "code.gitea.io/gitea/models/repo"
 	user_model "code.gitea.io/gitea/models/user"
@@ -403,16 +402,6 @@ func (g *GiteaLocalUploader) CreateIssues(issues ...*base.Issue) error {
 			Labels:      labels,
 			CreatedUnix: timeutil.TimeStamp(issue.Created.Unix()),
 			UpdatedUnix: timeutil.TimeStamp(issue.Updated.Unix()),
-			ForeignReference: &foreignreference.ForeignReference{
-				LocalIndex:   issue.GetLocalIndex(),
-				ForeignIndex: strconv.FormatInt(issue.GetForeignIndex(), 10),
-				RepoID:       g.repo.ID,
-				Type:         foreignreference.TypeIssue,
-			},
-		}
-
-		if is.ForeignReference.ForeignIndex == "0" {
-			is.ForeignReference.ForeignIndex = strconv.FormatInt(is.Index, 10)
 		}
 
 		if err := g.remapUser(issue, &is); err != nil {