Fix non-translatable multi-value fields loading as empty in Drupal 11.4.

The field-loading optimisation in SqlContentEntityStorage splits work into
loadSingleCardinalityFields() and loadMultipleCardinalityFields(). The
single-cardinality path guards the per-row langcode decision with
empty($row[$this->defaultLangcodeKey]) so that rows belonging to the default
translation are always keyed as LANGCODE_DEFAULT. The multiple-cardinality
path omits that guard, so when $row[$base_langcode_alias] differs from the
computed default langcode, a non-translatable multi-value field (e.g. an
entity_reference_revisions/paragraphs field) is skipped and loads 0 items,
making the content vanish on render and in edit forms.

This aligns the multiple-cardinality guard with the single-cardinality one.

--- a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php
+++ b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php
@@ -1596,7 +1596,7 @@
       // Field values in default language are stored with
       // LanguageInterface::LANGCODE_DEFAULT as key.
       $langcode = LanguageInterface::LANGCODE_DEFAULT;
-      if ($this->langcodeKey && isset($default_langcodes[$value_key]) && $row[$base_langcode_alias] != $default_langcodes[$value_key]) {
+      if ($this->langcodeKey && empty($row[$this->defaultLangcodeKey]) && isset($default_langcodes[$value_key]) && $row[$base_langcode_alias] != $default_langcodes[$value_key]) {
         $langcode = $row[$base_langcode_alias];
       }