ReadResourceHandler returns runtime values stored in the DMR model even if include-runtime=false

The transaction subsystem has a read-write runtime-only attribute whose value it stores in the resource's DMR model node. Its value is not persisted, so it really is runtime-only. (The value controls behavior of some runtime-only custom ops; this setup is basically a way of storing a semi-permanent param for those ops so it doesn't need to be passed with each invocation. Odd, but it is what it is.)

Problem is read-resource calls end up including the attribute when they should not:

[disconnected /] embed-server --admin-only=false
[standalone@embedded /] /subsystem=transactions/log-store=log-store:write-attribute(name=expose-all-logs,value=false)
{
    "outcome" => "success",
    "result" => undefined
}

[standalone@embedded /] /subsystem=transactions/log-store=log-store:read-resource(include-runtime=false)
{
    "outcome" => "success",
    "result" => {
        "expose-all-logs" => false,
        "type" => "default",
        "transactions" => undefined
    }
}

This happens because of ReadResourceHandler's behavior of trying to check for attributes in the DMR model that are not reflected in the ManagementResourceRegistration. Two possible fixes:

1) Make those checks a bit more sophisticated.

2) Remove that handling altogether as it's been at least five years since it was valid to have an attribute that is not reflected in the MRR.

I think I'll try #2.