Don't create empty iceberg delete file

[scanhex12]

Test "create empty table + delete some key" gives segfault.

Changelog category (leave one):

• Critical Bug Fix (crash, data loss, RBAC) or LOGICAL_ERROR

Changelog entry (a user-readable short description of the changes that goes into CHANGELOG.md):

Don't create empty iceberg delete file

Documentation entry for user-facing changes

• Documentation is written (mandatory for new features)

[clickhouse-gh]

Workflow [PR], commit [769071c]

Summary: ⏳

job_name	test_name	status	info	comment
Stateless tests (amd_binary, old analyzer, s3 storage, DatabaseReplicated, parallel)		failure
	Lost s3 keys	FAIL
	S3_ERROR No such key thrown (in clickhouse-server.log or clickhouse-server.err.log)	FAIL
Stateless tests (amd_debug, AsyncInsert, s3 storage, parallel)		failure
	01086_odbc_roundtrip	FAIL
Integration tests (arm_binary, distributed plan, 3/4)		failure
	test_global_overcommit_tracker/test.py::test_global_overcommit	FAIL
Integration tests (amd_tsan, 1/6)		failure
	test_checking_s3_blobs_paranoid/test.py::test_when_s3_connection_reset_by_peer_at_upload_is_retried[True]	FAIL
Integration tests (amd_asan, flaky check)		failure
	test_storage_iceberg/test.py::test_filesystem_cache[s3-1-3]	FAIL
	test_storage_iceberg/test.py::test_metadata_cache[azure-1-3]	FAIL
	test_storage_iceberg/test.py::test_metadata_cache[s3-2-3]	FAIL