[v25.3.x] bazel: update seastar to 3e8c2be0

[dotnwat]

Backport of PR #30692 to the v25.3.x branch.

Advances the Seastar pin to the head of redpanda-data/seastar#292, which
backports the fix for a concurrent put() on the socket in the OpenSSL TLS
backend (and its reproducer test) onto Seastar's v25.3.x branch.

• Seastar: 248de2a8 → e7973c89 — a direct descendant of the current pin;
  the only delta is the OpenSSL TLS fix, its reproducer, and CI-only tweaks.
• MODULE.bazel.lock updated to match the new pin.

Backports Required

• none - this is a backport

Release Notes

• none

🤖 Generated with Claude Code

[vbotbuildovich]

CI test results

test results on build#86196

test_status	test_class	test_method	test_arguments	test_kind	job_url	passed	reason	test_history
FAIL	src/v/storage/tests/storage_e2e_single_thread	src/v/storage/tests/storage_e2e_single_thread		unit	https://buildkite.com/redpanda/redpanda/builds/86196#019ef698-84db-4bf5-beab-30042efa6990	0/1

test results on build#86540

test_status	test_class	test_method	test_arguments	test_kind	job_url	passed	reason	test_history
FLAKY(PASS)	ShadowLinkingReplicationTests	test_auto_prefix_trimming	{"source_cluster_spec": {"cluster_type": "redpanda"}, "with_failures": true}	integration	https://buildkite.com/redpanda/redpanda/builds/86540#019f1a3b-aee6-4e9b-bdbf-e18449102d58	10/11	Test PASSES after retries.No significant increase in flaky rate(baseline=0.0094, p0=1.0000, reject_threshold=0.0100. adj_baseline=0.1000, p1=0.3487, trust_threshold=0.5000)	https://redpanda.metabaseapp.com/dashboard/87-tests?tab=142-dt-individual-test-history&test_class=ShadowLinkingReplicationTests&test_method=test_auto_prefix_trimming
FLAKY(PASS)	ShadowLinkingReplicationTests	test_replication_with_failures	null	integration	https://buildkite.com/redpanda/redpanda/builds/86540#019f1a3b-aee6-4e9b-bdbf-e18449102d58	10/11	Test PASSES after retries.No significant increase in flaky rate(baseline=0.0000, p0=1.0000, reject_threshold=0.0100. adj_baseline=0.1000, p1=0.3487, trust_threshold=0.5000)	https://redpanda.metabaseapp.com/dashboard/87-tests?tab=142-dt-individual-test-history&test_class=ShadowLinkingReplicationTests&test_method=test_replication_with_failures
FLAKY(PASS)	WriteCachingFailureInjectionTest	test_unavoidable_data_loss	null	integration	https://buildkite.com/redpanda/redpanda/builds/86540#019f1a3c-4fca-424f-ba9b-ac3b10bb3416	10/11	Test PASSES after retries.No significant increase in flaky rate(baseline=0.0952, p0=1.0000, reject_threshold=0.0100. adj_baseline=0.2594, p1=0.0497, trust_threshold=0.5000)	https://redpanda.metabaseapp.com/dashboard/87-tests?tab=142-dt-individual-test-history&test_class=WriteCachingFailureInjectionTest&test_method=test_unavoidable_data_loss
FLAKY(PASS)	TxAtomicProduceConsumeTest	test_basic_tx_consumer_transform_produce	{"with_failures": true}	integration	https://buildkite.com/redpanda/redpanda/builds/86540#019f1a3c-4fcb-46af-9ae5-9a20a5372329	10/11	Test PASSES after retries.No significant increase in flaky rate(baseline=0.0000, p0=1.0000, reject_threshold=0.0100. adj_baseline=0.1000, p1=0.3487, trust_threshold=0.5000)	https://redpanda.metabaseapp.com/dashboard/87-tests?tab=142-dt-individual-test-history&test_class=TxAtomicProduceConsumeTest&test_method=test_basic_tx_consumer_transform_produce