[TypePromotion] Add truncate in ConvertTruncs when the original truncate type is not extend type

If the src type is not extend type, after convert the truncate to and we need to truncate the and also to make sure the all user is legal.

The old fix D137613 doesn't work when the truncate convert to and have the other users. So this time I try to add the truncate after and to avoid all these potential issues.

Fix: #59554

Reviewed By: samparker

Differential Revision: https://reviews.llvm.org/D140869