Add window function drill tests for array_concat_agg for empty over scenarios

[Akshat-Jain]

Description

#16885 fixed issues with the following type of queries.

-- Query 1
select countryName, cityName, channel, array_concat_agg(ARRAY['N/A', countryName], 10000) over (order by countryName) as c
from wikipedia
where countryName in ('Austria', 'Republic of Korea') and (cityName in ('Horsching', 'Vienna', 'Seoul', 'Jeonju') or cityName is null)
group by countryName, cityName, channel

-- This query used to give InvalidNullByteException for MSQ engine.

-- Query 2
select
countryName, array_concat_agg(ARRAY[countryName], 10000) over () as c1
from wikipedia where countryName='Guatemala'
group by countryName

-- This used to give the following incorrect result for both sql-native and MSQ engines:
-- Guatemala	[""\t""]

This PR adds the above queries as drill tests so that the behavior is validated against both engines.

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This PR has:

• been self-reviewed.
• added documentation for new or modified features or behaviors.
• a release note entry in the PR description.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added or updated version, license, or notice information in licenses.yaml
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.
• added integration tests.
• been tested in a test Druid cluster.

[sreemanamala]

LGTM.