added iterator dst tests

[Lexert19]

Description

For #12537

This PR does not fully fix the TimeRangeIterator timezone bug, it adds reproducible tests that document the current behavior.

Changes in TimeRangeIteratorTest:

1. testNaturalMonthTimeRange – it's hardcoded to UTC.
2. Added testMonthOffsetCases() – tests monthly windows across DST transitions and historical offset changes:
3. Added testOffsetCases().
   This test is marked @ignore on purpose.
   org.apache.tsfile.utils.TimeDuration treats a day as a fixed physical duration of 86400000ms, not a calendar day in the given ZoneId. Because of that, daily windows drift on 23h/25h DST days and on historical offset changes.

The DateTimeUtils.toZoneOffset(ZoneId zoneId) fix has been moved to a separate issue.

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This PR has:

• [ x] been self-reviewed.
  • concurrent read
  • concurrent write
  • concurrent read and write
• added documentation for new or modified features or behaviors.
• added Javadocs for most classes and all non-trivial methods.
• added or updated version, license, or notice information
• [ x] 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.
• [x ] added integration tests.
• been tested in a test IoTDB cluster.

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