Before this commit, business code could leak records that are soft deleted, i.e. the representation of the record is still in the store but conceptually this record is deleted.

These soft-deleted records are present in the code for a very short time, just enough time to warn business code in the onDelete() hooks.

The problem for Model.records and Model.get() to return these records, is that the business code thinks these records are not deleted, which can lead to misuses and crashes.

For example: if a computed field returns this soft-deleted record, then the field value has this soft-deleted record. When the record is hard-deleted, this field will be recomputed, but when diffing with its old this will crash because it will still have a trace of the record in the internal code.

This commit fixes the issue by removing the record from Model.records when soft-deleted, so that Model.records and Model.get() doesn't return this record. The onDelete() hooks will returned the soft-deleted like before because the deleted records are stored in the data queue of the hooks.

This solution also solves another problem: if a record is deleted and there's an immediate side-effect computed field to insert this record, the previous implementation would hard-delete the record at the end which is wrong: the record should be deleted but the insert part should apply, thus the resulting record is a fresh one with same identity but only partial data from the insert. All other field values must be lost from the deletion. The changes in this commit also fixes this issue.

Commit also fixes issue for `.exists()` that should be `false` for soft-deleted records.

Task-4860196

Forward-Port-Of: odoo/odoo#224892
Forward-Port-Of: odoo/odoo#224485