[BugFix] Resolve Delete Semantics Data Loss in Flink SQL for StarRocks 3.1

[andystenhe]

In the 3.1 storage-computation separated version, using the INSERT INTO statement in Flink SQL will lose data with Delete semantics.

What type of PR is this：

• [v] BugFix
• [ ] Feature
• [ ] Enhancement
• [ ] Refactor
• [ ] UT
• [ ] Doc
• [ ] Tool

Which issues of this PR fixes ：

Fixes #364

Problem Summary(Required) ：

In the storage-computation separated version, the primary key information is not stored in the information_schema.COLUMNS table, causing the Flink connector to fail to detect the primary key and assume that the StarRocks table does not support writing Flink delete rowkind data.

Solution: Determine whether to support delete semantics based on the primary key declaration in the Flink table.

Checklist:

• [ ] I have added test cases for my bug fix or my new feature
• [ ] This pr will affect users' behaviors
• [ ] This pr needs user documentation (for new or modified features or behaviors)
• [ ] I have added documentation for my new feature or new function

[CLAassistant]

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