rptest/datalake_dlq_test: fix unintentional filesystem catalog

[andrwng]

Fixes to use the desired catalog parameter, which was unintentionally hard coded in #24947

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

[WillemKauf]

Oops! Thank you!

[vbotbuildovich]

CI test results

test results on build#61627

test_id	test_kind	job_url	test_status	passed
rptest.tests.cloud_storage_timing_stress_test.CloudStorageTimingStressTest.test_cloud_storage_with_partition_moves.cleanup_policy=compact.delete	ducktape	https://buildkite.com/redpanda/redpanda/builds/61627#0194d7b8-0f4f-4351-a9e8-aa48104b2152	FLAKY	1/2
rptest.tests.compaction_recovery_test.CompactionRecoveryTest.test_index_recovery	ducktape	https://buildkite.com/redpanda/redpanda/builds/61627#0194d7b1-ea94-4896-9bd6-b1b02a4e8850	FLAKY	1/2
rptest.tests.compaction_recovery_test.CompactionRecoveryUpgradeTest.test_index_recovery_after_upgrade	ducktape	https://buildkite.com/redpanda/redpanda/builds/61627#0194d7b1-ea95-422e-a8fc-71d2ced969ae	FLAKY	1/2
rptest.tests.datalake.compaction_test.CompactionGapsTest.test_translation_no_gaps.cloud_storage_type=CloudStorageType.S3.catalog_type=CatalogType.REST_JDBC	ducktape	https://buildkite.com/redpanda/redpanda/builds/61627#0194d7b8-0f4d-4b7b-ba92-4fdf73312d67	FLAKY	1/2
rptest.tests.scaling_up_test.ScalingUpTest.test_scaling_up_with_recovered_topic	ducktape	https://buildkite.com/redpanda/redpanda/builds/61627#0194d7b8-0f4f-4351-a9e8-aa48104b2152	FLAKY	1/4