test: Add integration tests for CDC table metadata

[dkropachev]

Summary

• Add comprehensive integration tests for ScyllaDB CDC table metadata in scylla_cdc_test.go
• 12 test scenarios covering CDC lifecycle: creation, ALTER enable/disable, options (preimage, postimage, TTL), drop propagation, cache staleness, and cold cache discovery
• The cdc_log_table_discoverable_without_cache test subscribes to schema change events and proves ScyllaDB does send CREATED events for CDC log tables — the issue is a race with the 1s event debouncer window

Test scenarios

Test	What it verifies
create_table_with_cdc_enabled	CDC extension + log table appear in metadata
create_table_without_cdc	No CDC extension or log table
enable_cdc_via_alter_table	ALTER TABLE adds CDC extension + log table
disable_cdc_via_alter_table	ALTER TABLE disabling CDC behavior
cdc_with_preimage_and_ttl	CDC options reflected in metadata
alter_cdc_options	Changing CDC options updates extension
cdc_log_table_discoverable_without_cache	Cold cache lookup with event logging + retry
cdc_log_table_has_expected_columns	CDC log columns (cdc$stream_id, cdc$time, cdc$operation)
drop_base_table_removes_cdc_log	DROP removes both base + log table
drop_base_table_cdc_log_not_stale_in_cache	Schema events clear cache (no manual invalidation)
scyllaIsCdcTable_detection	scyllaIsCdcTable() correctly identifies CDC vs base tables
cdc_with_postimage	Postimage option creates valid CDC setup

Key finding

The cdc_log_table_discoverable_without_cache test demonstrates that:

1. ScyllaDB sends schema change events for CDC log tables
2. ~48% of the time, the event hasn't been processed by the debouncer when GetTable is called immediately after CREATE TABLE
3. A 1s retry always resolves it

Test plan

• All 12 tests pass against ScyllaDB cluster (make scylla-start)
• 100/100 runs pass with retry logic
• Tests skip on Cassandra (CDC is a ScyllaDB-specific feature)

🤖 Generated with Claude Code