this change prepares for the fmt::formatter based formatter used by
tests, which will use {fmt} to print the elements in a container,
so we need to define the formatter using fmt::formatter for these
element. the operator<< for service_level_options::workload_type is
preserved, as the tests are still using it.
Refs #13245
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#17837
6244a2ae00