User specific repoID or xorm builder conditions for issue search (#19475)

* extend models.IssuesOptions to have more specific repo filter options

* use new options

* unrelated refactor

* rm RepoIDs

modules/indexer/issues/indexer.go

@@ -321,7 +321,7 @@ func populateIssueIndexer(ctx context.Context) {
 // UpdateRepoIndexer add/update all issues of the repositories
 func UpdateRepoIndexer(repo *repo_model.Repository) {
 	is, err := models.Issues(&models.IssuesOptions{
-		RepoIDs:  []int64{repo.ID},
+		RepoID:   repo.ID,
 		IsClosed: util.OptionalBoolNone,
 		IsPull:   util.OptionalBoolNone,
 	})