fix: apply the catalog's targetSegmentRows to MSQ ingestion

[FrankChen021]

Description

When an INSERT or REPLACE targets a catalog table with targetSegmentRows, DruidSqlValidator copies that value into the query context. It used the key msqRowsPerSegment, but MSQ reads rowsPerSegment (MultiStageQueryContext.CTX_ROWS_PER_SEGMENT). Nothing ever read msqRowsPerSegment, so the catalog value was ignored and MSQ used its default of 3,000,000 rows. The mismatch dates back to #15908.

This PR changes DruidSqlValidator.CTX_ROWS_PER_SEGMENT to rowsPerSegment. A rowsPerSegment set in the query context still takes precedence over the catalog value.

Release note

For SQL-based ingestion into a catalog table, the table's targetSegmentRows property now sets the target number of rows per segment. Previously it was ignored, and the default of 3,000,000 rows was used.

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Key changed/added classes in this PR

• DruidSqlValidator
• CalciteCatalogIngestionDmlTest

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This PR has:

• been self-reviewed.
• a release note entry in the PR description.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.

[FrankChen021]

🟢 Approval recommended

The corrected context key matches MSQ’s rowsPerSegment key, so catalog targetSegmentRows reaches MSQ tuning while explicit query-context values retain precedence. No actionable issue blocks merging.

Reviewed 2 of 2 changed files.

Validation: git diff --check passed. No builds or tests were run.

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This is an automated review by Codex GPT-5.6-Luna(max)