kafka/client: replace std::vector with chunked vector

[IoannisRP]

Replaced std::vector with chunked_vector in kafka client.

In case of a very big produce request, this vector caused an allocation warning.

Backports Required

• none - not a bug fix
• none - this is a backport
• none - issue does not exist in previous branches
• none - papercut/not impactful enough to backport
• v24.3.x
• v24.2.x
• v24.1.x

Release Notes

• none

[vbotbuildovich]

Retry command for Build#59809

please wait until all jobs are finished before running the slash command

/ci-repeat 1
tests/rptest/tests/cloud_retention_test.py::CloudRetentionTest.test_cloud_retention@{"cloud_storage_type":2,"max_consume_rate_mb":null}

[vbotbuildovich]

CI test results

test results on build#59809

test_id	test_kind	job_url	test_status	passed
rptest.tests.cloud_retention_test.CloudRetentionTest.test_cloud_retention.max_consume_rate_mb=None.cloud_storage_type=CloudStorageType.ABS	ducktape	https://buildkite.com/redpanda/redpanda/builds/59809#0193d05a-5b10-4e33-9505-c4a2827a532a	FAIL	0/6
rptest.tests.datalake.partition_movement_test.PartitionMovementTest.test_cross_core_movements.cloud_storage_type=CloudStorageType.S3	ducktape	https://buildkite.com/redpanda/redpanda/builds/59809#0193d056-78cd-4bf1-bf64-6de063b43d03	FLAKY	5/6
rptest.tests.datalake.partition_movement_test.PartitionMovementTest.test_cross_core_movements.cloud_storage_type=CloudStorageType.S3	ducktape	https://buildkite.com/redpanda/redpanda/builds/59809#0193d05a-5b13-4e4a-b684-9e07fe274265	FLAKY	3/6

[IoannisRP]

CI failures:

• CORE-8573