refactor(flyway): simplify address_utxo migration script

Remove unnecessary complexity from address_utxo migration as full database re-indexing eliminates the need for overly protective conditional logic.

Changes:
- Simplify V1.0_900_0 migration to direct index creation
- Remove conditional DO $$ block that checked for index existence
- Keep only essential index creation on address_utxo.tx_hash

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: 2 people

yaci-indexer/src/main/resources/db/store/postgresql/V1.0_900_0__rosetta_app_addres_utxo.sql

@@ -1,11 +1 @@
-DO $$
-BEGIN
-    IF NOT EXISTS (
-        SELECT 1 FROM pg_indexes
-        WHERE indexname = 'idx_address_utxo_tx_hash'
-        AND tablename = 'address_utxo'
-        AND schemaname = current_schema()
-    ) THEN
-        CREATE INDEX idx_address_utxo_tx_hash ON address_utxo USING btree (tx_hash);
-    END IF;
-END $$;
+CREATE INDEX idx_address_utxo_tx_hash ON address_utxo USING btree (tx_hash);