fixed issue #5391: skip unknown optional metadata types in TableMapLogEvent (#5577)

Replace IllegalArgumentException with buffer.forward(len) to gracefully
skip unrecognized optional metadata field types. This fixes crashes when
parsing binlog events from PolarDB or future MySQL versions that include
extended metadata types (e.g. type 72).

Fixes #5391

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>