Optimizer: HLL as the only cardinality candidate (drop Set/DeltaSet as cardinality values)

[milindsrivastava1997]

Change

For Statistic::Cardinality, the optimizer should consider HLL only: stop enumerating SetAggregator and DeltaSetAggregator as cardinality value aggregators.

• Planner-side filter only. Do not change asap_types::capability_matching::compatible_agg_types, which the engine's matcher and legacy planner use.
• DeltaSetAggregator stays as the key aggregator paired with keyed sketches.

Part of #753.

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