Revert "UniStore: Add folder to the SQL backend" (#95966)

Revert "UniStore: Add folder to the SQL backend (#95671)"

This reverts commit f075662696.

pkg/storage/unified/sql/testdata/sqlite--resource_update-single path.sql

@@ -2,7 +2,6 @@ UPDATE "resource"
     SET
         "guid"   = '',
         "value"  = '[]',
-        "folder"  = 'fldr',
         "action" = 'UNKNOWN'  
     WHERE 1 = 1
         AND "group"     = 'gg'