Hi Ganesh,
I understand that SAP note is for ECC 5.0 and your environment is CRM 7.0.
Objective of giving reference to that note is for the issue and solution described.
Solution is to drop the index and recreate it and proceed with upgrade.
As you have already dropped the index, re-create it and then continue with upgrade.
Hope this helps.
Regards,
Deepak Kori