Tables with a DECIMAL key column cannot be restored from backups

[jepett0]

Description

Please read the title.

Steps to reproduce

1. Create a table with a DECIMAL key column and at least 2 partitions:

create table test_decimal (
    key Decimal(22,9),
    value Utf8,
    primary key(key),
)
with (
    AUTO_PARTITIONING_BY_SIZE = ENABLED,
    AUTO_PARTITIONING_PARTITION_SIZE_MB = 1,
    AUTO_PARTITIONING_MIN_PARTITIONS_COUNT = 2
);

2. Fill the table so it would be split at least once:

huge_value definition

See the gist. Needs to be 100k+ symbols.

UPSERT INTO test_decimal (
    key,
    value
)
VALUES
    (CAST(1 as Decimal(22,9)), $huge_value),
    (CAST(2 as Decimal(22,9)), $huge_value),
    (CAST(3 as Decimal(22,9)), $huge_value),
    (CAST(4 as Decimal(22,9)), $huge_value),
    (CAST(5 as Decimal(22,9)), $huge_value),
    (CAST(6 as Decimal(22,9)), $huge_value),
    (CAST(7 as Decimal(22,9)), $huge_value),
    (CAST(8 as Decimal(22,9)), $huge_value),
    (CAST(9 as Decimal(22,9)), $huge_value),
    (CAST(10 as Decimal(22,9)), $huge_value),
    (CAST(11 as Decimal(22,9)), $huge_value),
    (CAST(12 as Decimal(22,9)), $huge_value),
    (CAST(13 as Decimal(22,9)), $huge_value),
    (CAST(14 as Decimal(22,9)), $huge_value),
    (CAST(15 as Decimal(22,9)), $huge_value),
    (CAST(16 as Decimal(22,9)), $huge_value),
    (CAST(17 as Decimal(22,9)), $huge_value),
    (CAST(18 as Decimal(22,9)), $huge_value),
    (CAST(19 as Decimal(22,9)), $huge_value),
    (CAST(20 as Decimal(22,9)), $huge_value);

3. Wait for about a minute, so the test_decimal table would be split. Check that there are at least 2 partitions in it.
4. Backup to S3 or call ydb tools dump --path test_decimal --scheme-only --output test_decimal_backup.
5. Drop the test_decimal table.
6. Restore from S3 or call ydb tools restore --path . --input test_decimal_backup depending on your choice at step 4.
7. Observe that:

• the export status is CANCELLED:

┌──────────────────────┬───────┬───────────┬───────────┬─────────────────────────┬────────────────────────┐
│ id                   │ ready │ status    │ progress  │ endpoint                │ bucket                 │
├──────────────────────┼───────┼───────────┼───────────┼─────────────────────────┼────────────────────────┤
│ ydb://import/8?id=84 │ true  │ CANCELLED │ Cancelled │ storage.yandexcloud.net │ ydb-backup-test-bucket │
│ 4424930141976&kind=s │       │           │           │                         │                        │
│ 3                    │       │           │           │                         │                        │
├╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴┴╴╴╴╴╴╴╴┴╴╴╴╴╴╴╴╴╴╴╴┴╴╴╴╴╴╴╴╴╴╴╴┴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴┴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴╴┤
│ Issues:                                                                                                 │
│   - <main>: Error: Error at split boundary 0: Unsupported typeId 4865 at index 0  

• or the restore produces an error:

Status: SCHEME_ERROR
Issues: 
<main>: Info: Path: /Root/dedicated/test_decimal
<main>: Error: Error at split boundary 0: Unsupported typeId 4865 at index 0