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>

models/issues/issue_test.go

@@ -7,13 +7,11 @@ import (
 	"context"
 	"fmt"
 	"sort"
-	"strconv"
 	"sync"
 	"testing"
 	"time"
 
 	"code.gitea.io/gitea/models/db"
-	"code.gitea.io/gitea/models/foreignreference"
 	issues_model "code.gitea.io/gitea/models/issues"
 	"code.gitea.io/gitea/models/organization"
 	repo_model "code.gitea.io/gitea/models/repo"
@@ -501,38 +499,6 @@ func TestCorrectIssueStats(t *testing.T) {
 	assert.EqualValues(t, issueStats.OpenCount, issueAmount)
 }
 
-func TestIssueForeignReference(t *testing.T) {
-	assert.NoError(t, unittest.PrepareTestDatabase())
-	issue := unittest.AssertExistsAndLoadBean(t, &issues_model.Issue{ID: 4})
-	assert.NotEqualValues(t, issue.Index, issue.ID) // make sure they are different to avoid false positive
-
-	// it is fine for an issue to not have a foreign reference
-	err := issue.LoadAttributes(db.DefaultContext)
-	assert.NoError(t, err)
-	assert.Nil(t, issue.ForeignReference)
-
-	var foreignIndex int64 = 12345
-	_, err = issues_model.GetIssueByForeignIndex(context.Background(), issue.RepoID, foreignIndex)
-	assert.True(t, foreignreference.IsErrLocalIndexNotExist(err))
-
-	err = db.Insert(db.DefaultContext, &foreignreference.ForeignReference{
-		LocalIndex:   issue.Index,
-		ForeignIndex: strconv.FormatInt(foreignIndex, 10),
-		RepoID:       issue.RepoID,
-		Type:         foreignreference.TypeIssue,
-	})
-	assert.NoError(t, err)
-
-	err = issue.LoadAttributes(db.DefaultContext)
-	assert.NoError(t, err)
-
-	assert.EqualValues(t, issue.ForeignReference.ForeignIndex, strconv.FormatInt(foreignIndex, 10))
-
-	found, err := issues_model.GetIssueByForeignIndex(context.Background(), issue.RepoID, foreignIndex)
-	assert.NoError(t, err)
-	assert.EqualValues(t, found.Index, issue.Index)
-}
-
 func TestMilestoneList_LoadTotalTrackedTimes(t *testing.T) {
 	assert.NoError(t, unittest.PrepareTestDatabase())
 	miles := issues_model.MilestoneList{