[FIX] base: ir.model.data: safer tests for index creation
[FIX] base: ir.model.data: safer tests for index creation

Complements b99ef3b125af374c4055908a56563d4da036be65.
The index definitions have changed, so we need distinct names
and existence tests to make sure they get properly created/altered
on older databases.

stephen144/odoo,optima-ict/odoo,stephen144/odoo,optima-ict/odoo,Elico-Corp/odoo_OCB,microcom/odoo,Elico-Corp/odoo_OCB,bplancher/odoo,dfang/odoo,ygol/odoo,hip-odoo/odoo,stephen144/odoo,sysadminmatmoz/OCB,sysadminmatmoz/OCB,microcom/odoo,storm-computers/odoo,storm-computers/odoo,microcom/odoo,stephen144/odoo,ygol/odoo,laslabs/odoo,sysadminmatmoz/OCB,bplancher/odoo,storm-computers/odoo,syci/OCB,dfang/odoo,ygol/odoo,stephen144/odoo,laslabs/odoo,optima-ict/odoo,ygol/odoo,syci/OCB,laslabs/odoo,dfang/odoo,ygol/odoo,Elico-Corp/odoo_OCB,microcom/odoo,syci/OCB,hip-odoo/odoo,stephen144/odoo,syci/OCB,hip-odoo/odoo,storm-computers/odoo,bplancher/odoo,Elico-Corp/odoo_OCB,dfang/odoo,ygol/odoo,laslabs/odoo,bplancher/odoo,syci/OCB,storm-computers/odoo,bplancher/odoo,sysadminmatmoz/OCB,hip-odoo/odoo,optima-ict/odoo,sysadminmatmoz/OCB,sysadminmatmoz/OCB,ygol/odoo,Elico-Corp/odoo_OCB,dfang/odoo,Elico-Corp/odoo_OCB,microcom/odoo,optima-ict/odoo,sysadminmatmoz/OCB,syci/OCB,hip-odoo/odoo,dfang/odoo,optima-ict/odoo,hip-odoo/odoo,storm-computers/odoo,microcom/odoo,bplancher/odoo,laslabs/odoo,laslabs/odoo