…eplacement test (#69349)

### What problem does this PR solve?

Issue Number: None

Related PR: #68084, #68100

Problem Summary:

**In short**


`MetaServiceTest.GetDeleteBitmapReturnsCompleteReplacementAfterTxnTooOld`
has failed on master since #68084 and #68100 were merged two minutes
apart on 2026-10-20, so the Cloud UT pipeline is red for every PR. The
test, added by #68100, injects a compaction aggregation without the
output rowset that #68084 started to require, so the meta service skips
the aggregation as obsolete. This PR adds that rowset to the test, the
way #68084 did for the other aggregation tests. It changes one line of a
test and no meta service code.

**Background**

- A compaction that aggregates the delete bitmaps of versions [start,
end] sends `update_delete_bitmap` with `lock_id = -3`, `without_lock`,
and `pre_rowset_agg_start_version` / `pre_rowset_agg_end_version`.
- #68084 makes the meta service check, in every transaction, that the
output rowset of such an aggregation still exists: the rowset meta at
the end version must exist and cover [start, end]. Otherwise the request
is treated as obsolete and returns OK without writing anything. #68084
added that output rowset (`put_delete_bitmap_test_rowset(..., 2, "r1-2",
1)`) to the existing tests that send such requests.
- #68100 added
`GetDeleteBitmapReturnsCompleteReplacementAfterTxnTooOld`. While
`get_delete_bitmap` reads a bitmap across several transactions, a sync
point injects an aggregation of [1, 2] and makes the read restart with
`TXN_TOO_OLD`; the test checks that the restarted read returns the
complete replacement. It was written against a master without #68084.

**The problem, and what it cost**

- With #68084, the injected aggregation has no output rowset at version
2, so `check_pre_rowset_aggregation` skips it. The restarted read
returns the old three-chunk bitmap, the byte threshold stops it before
`following_rowset`, and the first iteration fails:

```
cloud/test/meta_service_test.cpp:8501: Failure
Expected equality of these values:
  get_res.rowset_ids_size()
    Which is: 3
  expected_bitmap_count
    Which is: 4
Google Test trace:
cloud/test/meta_service_test.cpp:8382: replacement_size=1
```

- The ASSERT ends the test, so the second iteration (`replacement_size =
3 * DEFAULT_BLOB_SPLIT_SIZE`) never runs. `meta_service_test` exits
non-zero, and since 2026-10-20 11:16 +08:00 the Cloud UT pipeline has
failed for every PR, whatever the PR changes.
- branch-4.2 already has the pick of #68100 (#69307). Once the pick of
#68084 (#69306) is merged, branch-4.2 fails the same way.

**How this PR fixes it**

Add the output rowset of the injected aggregation to the test, as #68084
did for the other aggregation tests:

```cpp
put_delete_bitmap_test_rowset(meta_service.get(), instance_id, tablet_id, 2, "r1-2", 1);
```

With it, the check passes, the replacement is written, and the test
exercises the restarted read it was written for. Only that check reads
the new rowset meta; `get_delete_bitmap` does not read rowset metas, so
nothing else in the test changes.

**Results**

`run-cloud-ut.sh --run` in a Linux arm64 container (Debian 12, ldb
toolchain v0.25, the linux-aarch64 prebuilt third-party tree, a local
FDB 7.1.57):

| Run, on master `33c460d7365` |
`GetDeleteBitmapReturnsCompleteReplacementAfterTxnTooOld` | Other tests
|
|---|---|---|
| without this PR (the added line removed) | fails as on the pipeline: 3
rowset ids instead of 4, under `replacement_size=1` | not run |
| with this PR | passes | all 33 test binaries pass except
`StopWatchTest.SimpleTest` |

The same two runs on master `1d03523339f`, before the rebase, gave the
same results.

**Classes, and how they call each other**

```
MetaServiceTest.GetDeleteBitmapReturnsCompleteReplacementAfterTxnTooOld
 ├─ put_delete_bitmap_test_rowset(version 1, rowset_id)
 ├─ put_delete_bitmap_test_rowset(version 2, "r1-2", start 1)       <- added
 └─ MetaServiceImpl::get_delete_bitmap
      └─ sync point "get_delete_bitmap_err" (in the middle of the read)
           ├─ MetaServiceImpl::update_delete_bitmap(lock_id -3, aggregation [1, 2])
           │    └─ check_pre_rowset_aggregation: the rowset meta at version 2 must cover [1, 2]
           └─ TXN_TOO_OLD -> get_delete_bitmap restarts the read
```

Nothing outside `cloud/test/meta_service_test.cpp` changes.

**Merge order**

No dependency on master. On branch-4.2 this should go in together with
#69306 (the pick of #68084), or right after it.

Add an optional start_version argument to put_delete_bitmap_test_rowset and populate both rowset version bounds. The backported replacement test passes six arguments to a helper that still accepted five, which prevents Cloud UT from compiling.

Keep the existing five-argument callers compatible by defaulting the start version to the rowset end version. Match the helper already present on branch-4.2 so the aggregation output covers versions [1, 2].

Validation: clang-format 16 and git diff --check pass; the helper matches current branch-4.2. A local translation-unit syntax check is blocked by incompatible pre-generated Protobuf files and installed headers.