Fix decimal aggregates test for s390x

[HarryLeeIBM]

Functional test 00700_decimal_aggregates fails on s390x because the following SQL returns different results on LE and BE machines:

SELECT (uniqHLL12(a), uniqHLL12(b), uniqHLL12(c))
FROM (SELECT * FROM decimal ORDER BY a);

It returns (102,100,101) on LE machines and (99,101,102) on BE machines.

Actually both results are correct since HyperLogLog algorithm allows some small errors and it hashes LE numbers on LE machines and BE numbers on BE machines which causes different results(See the following code in src/AggregateFunctions/UniqVariadicHash.h).

struct UniqVariadicHash<false, false>
{
    static inline UInt64 apply(size_t num_args, const IColumn ** columns, size_t row_num)
    {
        UInt64 hash;

        const IColumn ** column = columns;
        const IColumn ** columns_end = column + num_args;

        {
            StringRef value = (*column)->getDataAt(row_num);
            hash = CityHash_v1_0_2::CityHash64(value.data, value.size);
            ++column;
        }

So the fix is to modify the SQL so that it works correct on both LE and BE machines.

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Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Fixed decimal aggregates functional test for x390x.

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[hanfei1991]

unrelated flaky test #49408