Nested cross-datastore references are not saved by JPA cascade operations

[knstvk]

Environment

Jmix version: 2.4.2

Steps To Reproduce

Add the following code to the data_stores.MultiDbDataManagerTest#testNestedCrossDatastoreEntitiesCascading method:

when:
def report1 = dataManager.load(MainReport)
        .id(report.id)
        .fetchPlan {
            it.addAll('db1OrderId', 'db1Order')
        }
        .one()

then:
report1.db1OrderId == order.id
report1.db1Order == order

The test will fail:

Condition not satisfied:

report1.db1OrderId == order.id
|       |          |  |     |
|       null       |  |     1
|                  |  test_support.entity.multidb.Db1Order-1 [detached]
|                  false
test_support.entity.multidb.MainReport-54192f61-5077-7f61-08ad-4730d7791858 [detached]