This commit allows for not copying the currency_field attribute
of a monetary field when the monetary field is related,
and when the currency_field attribute is not explicit
Before this commit, the currency_field attribute on the related monetary
was set as the one on the distant model
After this commit, the currency_field attribute takes the field on the
current model
Though the test may appear like an incoherent use case,
it is on the contrary totally legit, as web_studio allows it
OPW 1903113
closesodoo/odoo#28144
Lucas Perais (lpe)
50e5f73b4e