spanner-annotationsimpls-fixes (#102622)

* Fix DELETE statements.
* Reset sequence generator when truncating tables.
* Quote "at", since it's a keyword in Spanner.

pkg/services/annotations/annotationsimpl/xorm_store.go

@@ -333,10 +333,11 @@ func (r *xormRepositoryImpl) Get(ctx context.Context, query annotations.ItemQuer
 			}
 
 			if len(tags) > 0 {
+				// "at" is a keyword in Spanner and needs to be quoted.
 				tagsSubQuery := fmt.Sprintf(`
-			SELECT SUM(1) FROM annotation_tag at
-			INNER JOIN tag on tag.id = at.tag_id
-			WHERE at.annotation_id = a.id
+			SELECT SUM(1) FROM annotation_tag `+r.db.Quote("at")+`
+			INNER JOIN tag on tag.id = `+r.db.Quote("at")+`.tag_id
+			WHERE `+r.db.Quote("at")+`.annotation_id = a.id
 				AND (
 				%s
 				)