Replace go-migrate with morph (#19116)

db/migrations/postgres/000033_create_sidebar_channels.down.sql

@@ -0,0 +1,18 @@
+DO $$
+<<modify_column_type_if_type_is_different>>
+DECLARE
+    col_exist_and_type_different boolean := false;
+BEGIN
+    SELECT count(*) != 0 INTO col_exist_and_type_different
+    FROM information_schema.columns
+    WHERE table_name = 'sidebarchannels'
+    AND column_name = 'categoryid'
+    AND data_type = 'character varying'
+    AND NOT character_maximum_length = 26;
+
+    IF col_exist_and_type_different THEN
+        ALTER TABLE sidebarchannels ALTER COLUMN categoryid TYPE varchar(26);
+    END IF;
+END modify_column_type_if_type_is_different $$;
+
+DROP TABLE IF EXISTS sidebarchannels;