Fixing issue with row update not working for PK table:

[vamossagar12]

Purpose

Linked issue: close #2397

Brief change log

[FLUSS-2397] Fix UPDATE failure for primary key tables with computed columns

This commit fixes a bug where UPDATE statements failed when target tables
contained computed columns (e.g., PROCTIME). The root cause was that the
SinkWriter was using the table's physical RowType to initialize the
serialization schema, rather than the "consumed" RowType which includes
computed/metadata columns.

Key changes:

• Introduced 'consumedRowType' in FlinkSinkWriter, AppendSinkWriter, and
  UpsertSinkWriter to properly handle schema projection during serialization.
• Updated FlinkTableSink to ensure the correct row type is passed down to
  the writer.
• Added a regression test in FlinkTableSinkITCase that reproduces the
  reported failure (Bug Row UPDATE not working (PK Table) #2397).
• Updated internal builders and tests to accommodate the schema context.

Tests

fluss-flink/fluss-flink-common/src/test/java/org/apache/fluss/flink/sink/FlinkTableSinkITCase.java

API and Format

N/A

Documentation

N/A

[vamossagar12]

@polyzos , sorry for the delay- I got busy with other stuff. I created this PR. Please take a look!