Reduce precision of mapped ScalarDB BIGINT for Oracle from NUMBER(19) to NUMBER(16)

Author: Torch3333

core/src/main/java/com/scalar/db/storage/jdbc/RdbEngineOracle.java

@@ -204,7 +204,7 @@ public boolean isDuplicateIndexError(SQLException e) {
   public String getDataTypeForEngine(DataType scalarDbDataType) {
     switch (scalarDbDataType) {
       case BIGINT:
-        return "NUMBER(19)";
+        return "NUMBER(16)";
       case BLOB:
         return "RAW(2000)";
       case BOOLEAN: