Remove unused db calls

* virtual_interface_delete
* instance_get_all_by_project

Change-Id: Ie0b90802ccef72bd56d3508e7796194517f7a5ef
Remove unused db calls from nova.db.sqlalchemy.api

*  instance_metadata_get_item
*  _instance_system_metadata_get_item
*  instance_type_extra_specs_get_item
*  aggregate_metadata_get_item

Change-Id: If25db80f2fc2da1d26fd5588a5c24131fe05d24e
Merge "Remove unused db calls"
Merge "Remove unused db calls from nova.db.sqlalchemy.api"