Issue #3590655: Fix maxItems cardinality breaking multi-value saves

When maxItems is set on an array prop (e.g. maxItems: 5), the previous code passed that value as field cardinality. Drupal then renders N delta rows of entity_reference_autocomplete_tags. But the tags widget outputs all values in a single text input with name [prop][target_id] — no delta index — so all N rows share the same form element name. Only the last submitted value survives, meaning every save discards all but one item.

Fix: always use CARDINALITY_UNLIMITED for array types when the tags widget is in use. The tags widget is designed for one-input-for-all-values mode; finite cardinality is a JSON Schema concern enforced by Canvas validation, not a field cardinality concern. Non-tags widgets (via x-entity-widget override) still use maxItems as cardinality.