[CI] Fix false positive in database migration

- This also means that if one of the test fails, it will actually
propagate to make and subsequently fail the test.
- Remove the 'delete duplicates issue users' code, I checked this
against my local development database (which contains quite bizarre
cases, even some that Forgejo does not like), my local instance database
and against Codeberg production and they all yielded no results to this
query, so I'm removing it thus resolving the error that the delete code
was not compatible with Mysql.
- Sync all tables that are requires by the migration in the test.
- Resolves #2206

(cherry picked from commit 8e02be7e89)
(cherry picked from commit 006f064416)

models/migrations/v1_22/v283.go

@@ -8,23 +8,6 @@ import (
 )
 
 func AddCombinedIndexToIssueUser(x *xorm.Engine) error {
-	type OldIssueUser struct {
-		IssueID int64
-		UID     int64
-		Cnt     int64
-	}
-
-	var duplicatedIssueUsers []OldIssueUser
-	if err := x.SQL("select * from (select issue_id, uid, count(1) as cnt from issue_user group by issue_id, uid) a where a.cnt > 1").
-		Find(&duplicatedIssueUsers); err != nil {
-		return err
-	}
-	for _, issueUser := range duplicatedIssueUsers {
-		if _, err := x.Exec("delete from issue_user where id in (SELECT id FROM issue_user WHERE issue_id = ? and uid = ? limit ?)", issueUser.IssueID, issueUser.UID, issueUser.Cnt-1); err != nil {
-			return err
-		}
-	}
-
 	type IssueUser struct {
 		UID     int64 `xorm:"INDEX unique(uid_to_issue)"` // User ID.
 		IssueID int64 `xorm:"INDEX unique(uid_to_issue)"`