UCT/IB: Consume pending fence on send - revert UCT API changes (#11699)

* UCT/IB: Consume pending fence on send

A fence issued after rendezvous PUT remains pending until ATP is posted. If the next operation is another PUT, RC interprets the stale fence as a request for strong DDP ordering and adds an unnecessary fence.

Consume the pending fence when posting SEND in RC verbs and mlx5. Keep the UCP PUT-fence-ATP sequence so transports without PUT/AM ordering remain safe.

* UCT/IB: Cover DC fence consumption


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Signed-off-by: Roie Danino <rdanino@nvidia.com>