Fix incorrect early termination in descending scan of unpackOneFakeMemChunkMetaData

[shuwenwei]

Description

Problem

In the streaming query path of MemChunkLoader, unpackOneFakeMemChunkMetaData iterates through statisticsList to construct LazyMemVersionPageReader instances.

However, the original implementation always iterated statisticsList in ascending order while using the following early termination logic:

(orderUtils.getAscending() && orderTime > satisfiedTimeRange.getMax())
|| (!orderUtils.getAscending() && orderTime < satisfiedTimeRange.getMin())

When executing a descending scan, statisticsList is still ordered from small to large timestamps. This may cause the loop to break prematurely because the first element already satisfies orderTime < satisfiedTimeRange.getMin(), even though later elements could still fall within the query time range.

As a result, some valid pages may not be added to the page reader list, leading to missing data during descending scans.

Solution

This PR fixes the issue by iterating statisticsList according to the scan order:
• Ascending scan: iterate statisticsList in its natural order.
• Descending scan: iterate statisticsList in reverse order.

With this change, the early termination condition (break) becomes correct for both scan directions because the iteration order now matches the scan order.

The behavior is now consistent with the logic used in unpackOneChunkMetaData, where pageReaderList is also traversed differently depending on the scan order.

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

❌ Patch coverage is 0% with 24 lines in your changes missing coverage. Please review.
✅ Project coverage is 39.70%. Comparing base (ea3cc3c) to head (b8dad72).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...gine/execution/operator/source/SeriesScanUtil.java	0.00%	24 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #17283      +/-   ##
============================================
- Coverage     39.71%   39.70%   -0.01%     
  Complexity      282      282              
============================================
  Files          5100     5100              
  Lines        341950   341977      +27     
  Branches      43559    43562       +3     
============================================
- Hits         135798   135796       -2     
- Misses       206152   206181      +29     

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