Refactor tests (#33021)

1. fix incorrect tests, for example: BeanExists doesn't do assert and
shouldn't be used
2. remove unnecessary test functions
3. introduce DumpQueryResult to help to see the database rows during
test (at least I need it)

```
====== DumpQueryResult: SELECT * FROM action_runner_token ======
- # row[0]
  id: 1
  token: xeiWBL5kuTYxGPynHCqQdoeYmJAeG3IzGXCYTrDX
  owner_id: 0
...
```

models/issues/issue_user_test.go

@@ -12,6 +12,7 @@ import (
 	"code.gitea.io/gitea/models/unittest"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func Test_NewIssueUsers(t *testing.T) {
@@ -27,9 +28,8 @@ func Test_NewIssueUsers(t *testing.T) {
 	}
 
 	// artificially insert new issue
-	unittest.AssertSuccessfulInsert(t, newIssue)
-
-	assert.NoError(t, issues_model.NewIssueUsers(db.DefaultContext, repo, newIssue))
+	require.NoError(t, db.Insert(db.DefaultContext, newIssue))
+	require.NoError(t, issues_model.NewIssueUsers(db.DefaultContext, repo, newIssue))
 
 	// issue_user table should now have entries for new issue
 	unittest.AssertExistsAndLoadBean(t, &issues_model.IssueUser{IssueID: newIssue.ID, UID: newIssue.PosterID})