Update 105-update-root-area-and-iteration-path-field.sql

Based on [this discussion](https://chat.openshift.io/developers/pl/6m4cojtiotdoueqot8uww5ybpe) we first remove the unique name index on the `iterations` and `areas` table before we modify the data.

In a previous attempt (#2312) I haven't moved the removal of the index enough up.

This should fix the migration issue that was visible here: openshiftio/saas-openshiftio#1082

migration/sql-files/105-update-root-area-and-iteration-path-field.sql

@@ -1,11 +1,11 @@
--- append ID to non-root iteration and area paths
-UPDATE iterations SET path=text2ltree(concat(path, concat('.',replace(cast(id as text), '-', '_')))) WHERE path!='' AND path IS NOT NULL;
-UPDATE areas SET path=text2ltree(concat(path, concat('.',replace(cast(id as text), '-', '_')))) WHERE path!='' AND path IS NOT NULL;
-
 -- drop constraints
 ALTER TABLE iterations DROP CONSTRAINT iterations_name_space_id_path_unique;
 ALTER TABLE areas DROP CONSTRAINT areas_name_space_id_path_unique;
 
+-- append ID to non-root iteration and area paths
+UPDATE iterations SET path=text2ltree(concat(path, concat('.',replace(cast(id as text), '-', '_')))) WHERE path!='' AND path IS NOT NULL;
+UPDATE areas SET path=text2ltree(concat(path, concat('.',replace(cast(id as text), '-', '_')))) WHERE path!='' AND path IS NOT NULL;
+
 -- update root iteration and area paths to use converted ids
 UPDATE iterations SET path=text2ltree(replace(cast(id as text), '-', '_')) WHERE path='' OR PATH IS NULL;
 UPDATE areas SET path=text2ltree(replace(cast(id as text), '-', '_')) WHERE path='' OR PATH IS NULL;