core: Fix TestContext2Plan_createBefore_deposed
core: Fix TestContext2Plan_createBefore_deposed

This regressed after the recent changes to include deposed object changes
explicitly in the plan, since it was previously (correctly) asserting that
only the current object was covered by the plan.

Now we assert that both are present, and check that they have the correct
actions associated so that we are sure we're going to only delete the
deposed object and not the current object that sits alongside it.

hashicorp/terraform-plugin-sdk,hashicorp/terraform-plugin-sdk