Now that CDC is GA, it should be enabled in all the tests by default.
To achieve that the PR adds a special db::config::add_cdc_extension()
helper which is used in cql_test_envm to make sure CDC is usable in
all the tests that use cql_test_env.m As a result, cdc_tests can be
simplified.
Finally, some trailing whitespaces are removed from cdc_tests.
Tests: unit(dev)
Closes#7657
* github.com:scylladb/scylla:
cdc: Remove trailing whitespaces from cdc_tests
cdc: Remove mk_cdc_test_config from tests
config: Add add_cdc_extension function for testing
cdc: Add missing includes to cdc_extension.hh
5a9dc6a3cc