[fix](nereids) Fix DST spring-forward gap handling in timestamptz literal

[zclllyybb]

fix wrong timestamptz result when cast through DST.
before may ignore the DST.

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[zclllyybb]

/review

[Copilot]

Pull request overview

Fixes incorrect TIMESTAMPTZ literal evaluation when the specified local timestamp falls into a DST “spring-forward” gap (e.g., America/New_York at 2024-03-10 02:30:00), ensuring the literal is resolved to the correct instant instead of effectively ignoring the gap.

Changes:

• Replaced manual offset-difference adjustment logic in DateTimeLiteral with a LocalDateTime.atZone(...).withZoneSameInstant(...) conversion to correctly resolve DST gaps.
• Added a regression test suite + expected output covering named-zone, explicit-offset, and session-timezone (implicit) DST-gap literals and verifying equality.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
regression-test/suites/datatype_p0/timestamptz/test_timestamptz_dst_gap.groovy	New regression coverage for DST spring-forward gap behavior for TIMESTAMPTZ literals.
regression-test/data/datatype_p0/timestamptz/test_timestamptz_dst_gap.out	Expected results for the new DST-gap test queries.
fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/literal/DateTimeLiteral.java	Uses zone-aware conversion via withZoneSameInstant to correctly handle DST gaps during literal parsing.

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[zclllyybb]

run buildall

[zclllyybb]

run buildall

[zclllyybb]

/review

[github-actions]

No blocking issues found in this review.

Critical checkpoint conclusions:

• Goal/test coverage: The PR targets DST spring-forward gap handling for timestamptz/date-time literals. The implementation uses Java timezone resolution via LocalDateTime.atZone(...).withZoneSameInstant(...), and the new regression test covers explicit named-zone gap, explicit offsets around the gap, and implicit session-zone gap handling.
• Scope/focus: The change is small and focused on Nereids date/time literal timezone normalization plus one range guard.
• Concurrency/lifecycle/config: No concurrency, special lifecycle, or configuration changes are introduced.
• Compatibility/parallel paths: The reviewed string-literal cast and constant-folding paths continue to normalize explicit zones consistently; implicit TIMESTAMPTZ session-zone conversion already uses the same Java timezone conversion path through convert_tz.
• Error handling/data correctness: Range validation still runs after timezone conversion, and adding year < 0 prevents converted values before year 0000 from being silently accepted.
• Tests/results: The regression test follows the drop-before-use pattern and orders table output. I did not run the regression test in this review environment.
• Observability/performance: No additional observability is needed for this literal parsing fix; no material performance issue found.

User focus: No additional user-provided review focus was specified.

[zclllyybb]

run buildall

[zclllyybb]

run buildall

[github-actions]

PR approved by at least one committer and no changes requested.

[github-actions]

PR approved by anyone and no changes requested.