[FIX] Incorrect table alias used in joins

[tremlin]

Description of the issue/feature this PR addresses:
This PR contains the part of #1760 which has not been merged yet.

Current behavior before PR:

Suppose you have models with long names long.a and long.b where long.b inherits from long.a by _inherits. Then Odoo will generate the alias by joining the table names by two underscores. When the name exceeds the 64 character limit of PostgreSQL, Odoo will use a hash-based alias to stay within the limit. However, when preparing joins this alias is not used, which leads to broken SQL

SELECT "verylongtable111".id FROM "verylongtable3333" as "verylongtable111__verylongtable2222222222222_id__veryl_7647c3a2","verylongtable2222222222222" as "verylongtable111__verylongtable2222222222222_id","verylongtable111" WHERE ("verylongtable111"."verylongtable2222222222222_id"="verylongtable111__verylongtable2222222222222_id"."id" AND "verylongtable111__verylongtable2222222222222_id"."verylongtable3333_id"="verylongtable111__verylongtable2222222222222_id__verylongtable3333_id"."id") AND ("verylongtable111__verylongtable2222222222222_id__veryl_7647c3a2"."some_field" = 5) ORDER BY "verylongtable111"."id"  

In this case verylongtable111__verylongtable2222222222222_id__verylongtable3333_id is unknown to PostgreSQL. The alias should be used instead.

Desired behavior after PR is merged:

The correct table alias is used in all circumstances.

I confirm I have signed the CLA and read the PR guidelines at www.odoo.com/submit-pr

[lathama]

@tremlin is this PR still needed?