[Custom Processors] on coflict update

[keyliaran]

Description

fun insert_current_coin_balances (https://github.com/aptos-labs/aptos-indexer-processors/blob/main/rust/processor/src/processors/coin_processor.rs#L216). If two+ records with the same owner_address, coin_type_hash will be in one chunk, then insertion will be impossible (ON CONFLICT DO UPDATE).

Repro

INSERT INTO current_coin_balances (owner_address, coin_type_hash, coin_type,
                          amount, last_transaction_version, last_transaction_timestamp)
VALUES
    ('0x1', '0x1', 'test', 1, 1, now()),
    ('0x1', '0x1', 'test', 1, 2, now())
ON CONFLICT (owner_address, coin_type_hash) DO UPDATE
    SET
        amount = excluded.amount,
        last_transaction_version = excluded.last_transaction_version
WHERE current_coin_balances.last_transaction_version <= excluded.last_transaction_version;