`system_keyspace::read_cdc_generation_opt` queries
`system.cdc_generations_v3`, which stores ids of CDC generations
as timeuuids. This function shouldn't be called with a normal uuid
(used by `system.cdc_generations_v2` to store generation ids).
Such a call would end with a marshaling error.
Before this patch,`retrieve_generation_data_v2` could call
`system_keyspace::read_cdc_generation_opt` with a normal uuid if
the generation wasn't present in `system.cdc_generations_v2`.
This logic caused a marshaling error while handling the
`check_and_repair_cdc_streams` request in the
`cdc_test.TestCdc.test_check_and_repair_cdc_streams_liveness` dtest.
This patch fixes the code being added in 6.0, no need to backport it.
Fixesscylladb/scylladb#18473Closesscylladb/scylladb#18483
628d7e709e