MDEV-15990 innodb: change DB_FOREIGN_DUPLICATE_KEY to DB_DUPLICATE_KEY

during row insert

DB_FOREIGN_DUPLICATE_KEY in row_ins_duplicate_error_in_clust was
motivated by handling the cascade changes during versioned operations.

It was found though, that certain row_update_for_mysql calls could
return DB_FOREIGN_DUPLICATE_KEY, even if there's no foreign relations.

Change DB_FOREIGN_DUPLICATE_KEY to DB_DUPLICATE_KEY in
row_ins_duplicate_error_in_clust.

It will be later converted to DB_FOREIGN_DUPLICATE_KEY in
row_ins_check_foreign_constraint if needed.

Additionally, ha_delete_row should return neither. Ensure it by an
assertion.

Author: FooBarrior

storage/innobase/handler/ha_innodb.cc

@@ -8719,6 +8719,9 @@ ha_innobase::delete_row(
 	ut_ad(!trx->is_bulk_insert());
 	error = row_update_for_mysql(m_prebuilt);
 
+	ut_ad(error != DB_DUPLICATE_KEY);
+	ut_ad(error != DB_FOREIGN_DUPLICATE_KEY);
+
 #ifdef WITH_WSREP
 	if (error == DB_SUCCESS && trx->is_wsrep()
 	    && wsrep_thd_is_local(m_user_thd)

storage/innobase/row/row0ins.cc

@@ -2409,7 +2409,7 @@ row_ins_duplicate_error_in_clust(
 						&trx_id_len);
 					ut_ad(trx_id_len == DATA_TRX_ID_LEN);
 					if (trx->id == trx_read_trx_id(trx_id)) {
-						err = DB_FOREIGN_DUPLICATE_KEY;
+						err = DB_DUPLICATE_KEY;
 					}
 				}
 				goto func_exit;