[flink] Fix TableNotExistException when listing partitions on changelog / binlog virtual tables

[naivedogger]

Purpose

Linked issue: close #3640

When the Flink optimizer calls listPartitions() on a $changelog or $binlog virtual table, it throws TableNotExistException because the virtual table suffix is not stripped before querying the Fluss server.

getTable() correctly dispatches virtual table names to getVirtualChangelogTable()/getVirtualBinlogTable(), but tableExists(), listPartitions(), createPartition(), and dropPartition() all pass the unstripped virtual table name directly to the admin API, which fails because no physical table named xxx$changelog exists.

Brief change log

• Added toPhysicalTablePath() private helper method to FlinkCatalog that strips $changelog, $binlog, and $lake suffixes from the table name, returning the base physical table path
• Updated tableExists() to use toPhysicalTablePath() — virtual tables now correctly report existence based on the base table
• Updated listPartitions(ObjectPath, CatalogPartitionSpec) to use toPhysicalTablePath() — virtual tables now list partitions of the base table
• Updated createPartition() and dropPartition() to use toPhysicalTablePath() — partition management through virtual table names delegates to the base table

Tests

• Added FlinkCatalogTest#testVirtualTablePartitionsAndExistence which verifies:
  • tableExists() returns true for $changelog and $binlog virtual table names
  • listPartitions() returns the same partitions as the base table for both virtual table suffixes
  • listPartitions() with a CatalogPartitionSpec works correctly on virtual table names
  • createPartition() and dropPartition() work through virtual table names
• Existing FlinkCatalogTest#testOperatePartitions continues to pass (no regression)

API and Format

No API or storage format changes. The fix only affects internal catalog method behavior for virtual table names.

Documentation

No documentation changes needed — this is a bug fix that makes virtual table behavior consistent with getTable().