default void dropConstraint(String catName, String dbName, String tableName,
                              String constraintName) throws NoSuchObjectException {
    dropConstraint(catName, dbName, tableName, constraintName, false);
  }
Drop a constraint, any constraint.  I have no idea why add and get each have separate
methods for each constraint type but drop has only one.
@param catName catalog name
@param dbName database name
@param tableName table name
@param constraintName name of the constraint
@throws NoSuchObjectException no constraint of this name exists
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/RawStore.java