Select fileds rathert * to read snapshot data in case schema changes.

[loserwang1024]

Fix https://issues.apache.org/jira/browse/FLINK-39071

[Copilot]

Pull request overview

Updates Postgres snapshot split scanning to select an explicit column list (instead of *) so snapshot reads are more robust when the underlying table schema changes (FLINK-39071).

Changes:

• Extend PostgresQueryUtils.buildSplitScanQuery to optionally accept a column projection list.
• Update PostgresScanFetchTask to build and pass a quoted column list from the Debezium Table schema for snapshot queries.
• Simplify the internal query builder path by removing unused split-query branching/limit handling.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
.../utils/PostgresQueryUtils.java	Adds a column-projection overload for split scan queries and simplifies select query construction.
.../fetch/PostgresScanFetchTask.java	Builds an explicit quoted column list from the schema and uses it for snapshot split SELECT statements.

Comments suppressed due to low confidence (1)

flink-cdc-connect/flink-cdc-source-connectors/flink-connector-postgres-cdc/src/main/java/org/apache/flink/cdc/connectors/postgres/source/utils/PostgresQueryUtils.java:321

• buildSelectWithRowLimits no longer applies any LIMIT clause (the limit parameter and logic were removed), so the method name is now misleading and the remaining buildSelectWithBoundaryRowLimits/get*Projection helpers appear to be unused. Consider either renaming this method to reflect its current behavior and removing the now-dead boundary/PK projection helpers, or reintroducing a limit parameter if limiting is still required elsewhere.

    private static String buildSelectWithRowLimits(
            TableId tableId,
            String projection,
            Optional<String> condition,
            Optional<String> orderBy) {
        final StringBuilder sql = new StringBuilder("SELECT ");

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