Column uniqueness constrain should only apply to inner join

// RelMdColumnUniqueness.areColumnsUnique(Join rel, RelMetadataQuery mq ...

final Double rightMaxRowCount = mq.getMaxRowCount(right);
if (rightMaxRowCount != null && rightMaxRowCount <= 1.0) {
  leftColumns = leftColumns.union(joinInfo.leftSet());
}
final Double leftMaxRowCount = mq.getMaxRowCount(left);
if (leftMaxRowCount != null && leftMaxRowCount <= 1.0) {
  rightColumns = rightColumns.union(joinInfo.rightSet());
} 

@Test void testColumnUniquenessForJoinOnLimit1() {
  final String sql = ""
      + "select *\n"
      + "from emp A\n"
      + "join (\n"
      + "  select * from emp\n"
      + "  limit 1) B\n"
      + "on A.empno = B.empno";
  sql(sql)
      .assertThatAreColumnsUnique(bitSetOf(0), is(true))
      .assertThatAreColumnsUnique(bitSetOf(1), is(true))
      .assertThatAreColumnsUnique(bitSetOf(9), is(true))
      .assertThatAreColumnsUnique(bitSetOf(10), is(true))
      .assertThatAreColumnsUnique(bitSetOf(), is(true))
      .assertThatUniqueKeysAre(bitSetOf());
}