storage: break, not co_return, in adjacent_merge_compact()

[WillemKauf]

For the purpose of making forward progress with adjacent merge compaction, we should not need to self compact every segment in the log before attempting adjacent compaction.

Change this co_return to a break to attempt adjacent merge compaction after self compacting a single segment.

Tagged for backports.

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

Improvements

• Allow adjacent merge compaction to make more forward progress when log_compaction_use_sliding_window is disabled.

[vbotbuildovich]

CI test results

test results on build#62038

test_id	test_kind	job_url	test_status	passed
rptest.tests.cloud_storage_scrubber_test.CloudStorageScrubberTest.test_scrubber.cloud_storage_type=CloudStorageType.S3	ducktape	https://buildkite.com/redpanda/redpanda/builds/62038#0195205d-7ec2-4e69-94f8-4fa25be2ee6c	FLAKY	1/2
rptest.tests.compaction_recovery_test.CompactionRecoveryTest.test_index_recovery	ducktape	https://buildkite.com/redpanda/redpanda/builds/62038#0195205d-7ec1-47e1-a291-14d8dcb3cb0d	FLAKY	1/3
rptest.tests.compaction_recovery_test.CompactionRecoveryTest.test_index_recovery	ducktape	https://buildkite.com/redpanda/redpanda/builds/62038#01952060-7ae1-440b-afd1-08aeaf1f3a3e	FLAKY	1/2
rptest.tests.log_compaction_test.LogCompactionTest.compaction_stress_test.cleanup_policy=compact.key_set_cardinality=1000.storage_compaction_key_map_memory_kb=3	ducktape	https://buildkite.com/redpanda/redpanda/builds/62038#01952060-7ae0-4094-80d7-f5bfc37a611d	FLAKY	1/3
rptest.tests.partition_movement_test.SIPartitionMovementTest.test_shadow_indexing.num_to_upgrade=0.cloud_storage_type=CloudStorageType.S3	ducktape	https://buildkite.com/redpanda/redpanda/builds/62038#01952060-7ae1-440b-afd1-08aeaf1f3a3e	FLAKY	1/2
rptest.tests.scaling_up_test.ScalingUpTest.test_scaling_up_with_recovered_topic	ducktape	https://buildkite.com/redpanda/redpanda/builds/62038#01952060-7ae0-4094-80d7-f5bfc37a611d	FLAKY	1/3
rptest.tests.simple_e2e_test.SimpleEndToEndTest.test_relaxed_acks.write_caching=False	ducktape	https://buildkite.com/redpanda/redpanda/builds/62038#01952060-7ade-4fad-95e7-3f85d282e213	FLAKY	1/2

test results on build#62076

test_id	test_kind	job_url	test_status	passed
rptest.tests.delete_records_test.DeleteRecordsTest.test_delete_records_concurrent_truncations.cloud_storage_enabled=True.truncate_point=random_offset	ducktape	https://buildkite.com/redpanda/redpanda/builds/62076#0195258b-4658-4214-ad86-8736b1cf1fab	FLAKY	1/2
rptest.tests.partition_movement_test.SIPartitionMovementTest.test_shadow_indexing.num_to_upgrade=0.cloud_storage_type=CloudStorageType.ABS	ducktape	https://buildkite.com/redpanda/redpanda/builds/62076#0195258f-d19e-47d3-9369-93ab4c3327cd	FLAKY	1/2
rptest.tests.random_node_operations_test.RandomNodeOperationsTest.test_node_operations.enable_failures=True.mixed_versions=False.with_tiered_storage=True.with_iceberg=False.with_chunked_compaction=False.cloud_storage_type=CloudStorageType.ABS	ducktape	https://buildkite.com/redpanda/redpanda/builds/62076#0195258f-d19e-47d3-9369-93ab4c3327cd	FLAKY	1/2

[WillemKauf]

Force push to:

• Rebase to upstream/dev to fix merge conflicts