fix: block inverted index V1 creation in FE [DORIS-26415]

[LIANG751234313]

Proposed changes

Issue Number: close #DORIS-26415

Problem

When users copy historical DDL statements that explicitly set inverted index format to V1, new tables are silently created with V1. Inverted index V1 does not support small file merging and bypasses the packed file path, significantly amplifying PUT requests to object storage.

Observed impact: clusters with high write QPS are seeing300–400 PUT/s, with 70–80% attributed to inverted index V1.

Solution

Block new inverted index V1 creation at the FE level:

• Explicitly specifying inverted_index_storage_format = v1 on a new indexnow returns an error immediately.
• Users are guided to use V2 (the default).
• Existing V1 tables remain fully compatible — metadata loading and read/write
  are unaffected. No forced migration.

Error message:Inverted index V1 is deprecated and no longer allowed for new index creation.Please use inverted index V2.

Coverage

• CREATE TABLE with inline index definition
• ALTER TABLE ADD INDEX
• All other code paths that create a new inverted index

Checklist

• Does it affect the existing behavior? No — only blocks new V1 creation;existing V1 tables are untouched.
• V2 is still used by default when the version is not specified.
• Has unit/regression test been added? Yes — FE regression test added.

[hello-stephen]

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