Remove legacyCreateMultiple function

This was annotated deprecated 7 years ago, is called 'legacy' and was nosily deprecated 10 months
ago. It IS still called from one jma extenion but I think it's OK to remove with a ping

CRM/Contact/BAO/Relationship.php

@@ -141,85 +141,6 @@ public static function createMultiple($params, $primaryContactLetter) {
     ];
   }
 
-  /**
-   * Only called from import now... plus one place outside of core & tests.
-   *
-   * @todo - deprecate more aggressively - will involve copying to the import
-   * class, adding a deprecation notice here & removing from tests.
-   *
-   * Takes an associative array and creates a relationship object.
-   *
-   * @deprecated For single creates use the api instead (it's tested).
-   * For multiple a new variant of this function needs to be written and migrated to as this is a bit
-   * nasty
-   *
-   * @param array $params
-   *   (reference ) an assoc array of name/value pairs.
-   * @param array $ids
-   *   The array that holds all the db ids.
-   *   per http://wiki.civicrm.org/confluence/display/CRM/Database+layer
-   *  "we are moving away from the $ids param "
-   *
-   * @return array
-   * @throws \CRM_Core_Exception
-   */
-  public static function legacyCreateMultiple($params, $ids = []) {
-    CRM_Core_Error::deprecatedFunctionWarning('api v4');
-    // clarify that the only key ever pass in the ids array is 'contact'
-    // There is legacy handling for other keys but a universe search on
-    // calls to this function (not supported to be called from outside core)
-    // only returns 2 calls - one in CRM_Contact_Import_Parser_Contact
-    // and the other in jma grant applications (CRM_Grant_Form_Grant_Confirm)
-    // both only pass in contact as a key here.
-    $contactID = $ids['contact'];
-    unset($ids);
-    // There is only ever one value passed in from the 2 places above that call
-    // this - by clarifying here like this we can cleanup within this
-    // function without having to do more universe searches.
-    $relatedContactID = key($params['contact_check']);
-
-    // check if the relationship is valid between contacts.
-    // step 1: check if the relationship is valid if not valid skip and keep the count
-    // step 2: check the if two contacts already have a relationship if yes skip and keep the count
-    // step 3: if valid relationship then add the relation and keep the count
-
-    // step 1
-    [$contactFields['relationship_type_id'], $firstLetter, $secondLetter] = explode('_', $params['relationship_type_id']);
-    $contactFields['contact_id_' . $firstLetter] = $contactID;
-    $contactFields['contact_id_' . $secondLetter] = $relatedContactID;
-    if (!CRM_Contact_BAO_Relationship::checkRelationshipType($contactFields['contact_id_a'], $contactFields['contact_id_b'],
-      $contactFields['relationship_type_id'])) {
-      return [0, 0];
-    }
-
-    //CRM-16978:check duplicate relationship as per case id.
-    // https://issues.civicrm.org/jira/browse/CRM-16978
-    if ($caseId = CRM_Utils_Array::value('case_id', $params)) {
-      CRM_Core_Error::deprecatedWarning('this code is believed to be unreachable');
-      $contactFields['case_id'] = $caseId;
-    }
-    if (
-    self::checkDuplicateRelationship(
-      $contactFields,
-      (int) $contactID,
-      // step 2
-      (int) $relatedContactID
-    )
-    ) {
-      return [0, 1];
-    }
-
-    $singleInstanceParams = array_merge($params, $contactFields);
-    $relationship = self::add($singleInstanceParams);
-
-    // do not add to recent items for import, CRM-4399
-    if (empty($params['skipRecentView'])) {
-      self::addRecent($params, $relationship);
-    }
-
-    return [1, 0];
-  }
-
   /**
    * This is the function that check/add if the relationship created is valid.
    *