branch-4.2: [fix](be) Preserve JSON and WAL rows with empty file projections #70154 - #70180

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### What problem does this PR solve?

Issue Number: close #69926

Problem Summary:

Hive JSON queries that only need partition columns can return zero rows
even when the selected files contain records. For example, `SELECT * ...
WHERE dt = 'p1'` returns data while `SELECT COUNT(*) ... WHERE dt =
'p1'` returns zero. The V2 JSON reader derived its row count from the
output block, which has no columns after physical field pruning.
Writer-backed reader tests reproduce the same row-count loss for empty
WAL projections.

Track accepted JSON records independently of materialized columns,
including batch progress, array expansion, error rollback, and
ignore-malformed NULL rows. Preserve JSON-path record selection for
empty projections, and let the existing TableReader materialize
partition values using the returned row count.

For WAL, save the deserialized source row count before materialization
transfers column ownership, then pass it through the existing filter
pipeline. This preserves the row count when no file columns are
requested. The empty-projection reproduction is at the reader interface;
production replay reachability of an empty projection remains
unverified.

Add ten JSON BE tests covering empty file schemas and projections,
arrays, JSON roots/paths, malformed input, batch boundaries, EOF, and
actual TableReader partition materialization. Add eight writer-backed
WAL cases covering empty, single-column, and reordered full projections
across multiple blocks, with and without schema discovery, plus repeated
EOF reads. Add a WAL SQL regression that forces two original async-load
transactions to abort, then verifies row counts, NULLs, aggregates,
filters, and actual values after replay. Add a Hive SQL regression using
the existing partitioned JSON fixture for COUNT, partition projections,
grouping, and file-column filters with external COUNT pushdown enabled
and disabled.

### Release note

Fix incorrect zero counts and missing rows when querying only partition
columns of Hive JSON tables. Preserve logical row counts for empty WAL
reader projections.

### Check List (For Author)

- Test
- [x] Unit Test: 166 ASAN tests passed, including JSON reader,
TableReader, WAL V2 reader, WAL reader/writer, and CSV/Text
empty-projection controls. Before the JSON fix, nine of ten new tests
failed; before the WAL fix, both empty-projection cases failed while six
projection controls passed.
- [x] WAL SQL regression: `test_group_commit_wal_row_count` passed twice
on isolated Doris 4.1.5 with scanner V2 enabled. Generated the `.out`
file with `run-regression-test.sh`, then reran for result comparison.
Execution on master is pending CI.
- [x] Hive SQL regression: added `test_hive_json_partition_only`; Groovy
compilation passed. Full execution against the external Hive fixture is
pending CI.
- Behavior changed:
- [x] Yes. Empty JSON and WAL file projections preserve logical row
counts. Hive JSON partition-only queries produce the correct rows and
aggregates.
- Does this need documentation?
    - [x] No.