Fix: scheduler: properly compute digest of non-sensitive resource parameters

The controller records op-secure-digest as a hash of all resource parameters
(specifically, those listed in the resource agent's meta-data) except those
marked as private.

Previously, the scheduler compared that against a digest of *all* parameters
(including meta-attributes, etc.) after filtering private parameters and
running pcmk__filter_op_for_digest(). The latter usually made the hash
identical to the controller's, but not always. Now, it only digests resource
instance attributes.