[v25.2.x] Update libxml2 2.14.5

[BenPope]

Backport of #27198

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
• v25.2.x
• v25.1.x
• v24.3.x

Release Notes

• none

[vbotbuildovich]

CI test results

test results on build#70620

test_class	test_method	test_arguments	test_kind	job_url	test_status	passed	reason
RandomNodeOperationsTest	test_node_operations	{"cloud_storage_type": 1, "compaction_mode": "adjacent_merge", "enable_failures": false, "mixed_versions": false, "with_iceberg": true}	integration	https://buildkite.com/redpanda/redpanda/builds/70620#01989d12-975d-41ec-8b50-45477085a279	FLAKY	20/21	upstream reliability is '100.0'. current run reliability is '95.23809523809523'. drift is 4.7619 and the allowed drift is set to 50. The test should PASS
RandomNodeOperationsTest	test_node_operations	{"cloud_storage_type": 2, "compaction_mode": "sliding_window", "enable_failures": true, "mixed_versions": true, "with_iceberg": false}	integration	https://buildkite.com/redpanda/redpanda/builds/70620#01989d12-9755-4243-b7a5-84627424e282	FLAKY	19/21	upstream reliability is '100.0'. current run reliability is '90.47619047619048'. drift is 9.52381 and the allowed drift is set to 50. The test should PASS