The docs imply that when specified the `on` option of
`validates_associated` should be respected by the validated association.
Prior to this change the validation context used will simply be the
default behavior as if no `on` option were specified. With this change,
the validation_context of the parent record is passed to the `valid?`
check.

When associations are created or updated allow them to use their own
default context according to their own persistence status rather than
overriding with the context of their associated object.

Fixes #46239

Co-authored-by: Alex Ghiculescu <alex@tanda.co>
Co-authored-by: Rafał Brize <rafal@buyapowa.com>