pbss: support to load legacy async buffer format

[galaio]

Description

This PR fixes a legacy journal format issue, it tries to load an async buffer in a legacy journal file.

When the PR is enabled, the node can read the async buffer correctly.

logs/bsc.log.2024-12-20_11:t=2024-12-20T11:15:10+0000 lvl=info msg="New async node buffer" limit="256.00 MiB" layers=44221
logs/bsc.log.2024-12-20_12:t=2024-12-20T12:15:37+0000 lvl=info msg="Failed to load journal, discard it" err="unexpected journal version want 2 got 0"

It will fix the issue #2796.

Changes

Notable changes:

• pbss: support to load legacy async buffer format;
• ...

[galaio]

PBSS journal history change:

1. journal ver1, core/state, trie/triedb/pathdb: remove storage incomplete flag ethereum/go-ethereum#28940
2. journal ver2, triedb/pathdb: track flat state changes in pathdb (snapshot integration pt 2) ethereum/go-ethereum#30643

The async buffer saved in the journal only changes in ver2, so we need to handle the legacy async buffer ver0/ver1 in the same way.