rich-indexer: Do not insert uncle block into database

[eval-exec]

What problem does this PR solve?

For rich-indexer, we don't really need to insert uncle block related info into database. This PR remove the related logic.

Related changes

• Remove the uncle block logic for rich-indexer

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code ci-runs-only: [ quick_checks,linters ]

Side effects

• None

Release note

Note: Rich Indexer: Uncle Block Tracking Removed

The rich-indexer no longer tracks uncle blocks. The `block_association_uncle` table has been removed from the schema.

**Action Required:** If you have an existing rich-indexer database, manually drop the unused table: DROP TABLE block_association_uncle;

[doitian]

Suggest adding a release note that user can delete the table by running SQL DROP table xxx

[eval-exec]

Suggest adding a release note that user can delete the table by running SQL DROP table xxx

Done