ddl: Remove field "comment" from TiDB::TableInfo

[JaySon-Huang]

What problem does this PR solve?

Issue Number: close #9497

Problem Summary:

The "comment" field in TableInfo is useless for TiFlash. And also it could contain some user info of the table def. Removing them from TiFlash is more reasonable.

What is changed and how it works?

ddl: Remove field "comment" from TiDB::TableInfo

  * Remove `comment` field from `TableInfo`, `ColumnInfo`, etc
  * Remove `table_name` from `IndexInfo` because it is useless
  * Remove storage_engine_type from `TableInfo`. We used to use it to create "StorageDeltaMerge" or "StorageTransactionMergeTree" before v4.0 is released. But the later one has been totally removed from TiFlash.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility
  • Older version tiflash binary require the "comment" field when parsing. This PR will make in-place downgrade failed

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None

[JaySon-Huang]

Remove because it is conflict with those default value defined in TiDB.h

tiflash/dbms/src/TiDB/Schema/TiDB.h

Lines 241 to 260 in 20e5abf

	struct IndexInfo
	{
	IndexInfo() = default;
	explicit IndexInfo(Poco::JSON::Object::Ptr json);
	Poco::JSON::Object::Ptr getJSONObject() const;
	void deserialize(Poco::JSON::Object::Ptr json);
	Int64 id = -1;
	String idx_name;
	std::vector<IndexColumnInfo> idx_cols;
	SchemaState state = StatePublic;
	Int32 index_type = -1;
	bool is_unique = false;
	bool is_primary = false;
	bool is_invisible = false;
	bool is_global = false;
	};

[CalvinNeo]

lgtm

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: CalvinNeo, JinheLin

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• OWNERS [CalvinNeo,JinheLin]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-08-21 14:55:24.859159497 +0000 UTC m=+363719.993609627: ☑️ agreed by JinheLin.
• 2024-08-22 02:49:30.105083072 +0000 UTC m=+406565.239533193: ☑️ agreed by CalvinNeo.