The function database::create_local_system_table calls
get_tables_metadata().hold_write_lock(), but does not co_await the
returned future. Effectively, this code does not guarantee mutual
exclusion because it does not wait for the lock to be acquired and does
not guarantee that the lock is held long enough.
Fix this by adding the co_await that was missing.
Found by manual inspection. This code is not known to have caused any
problems so far, but it's clearly wrong - hence the fix.
Closesscylladb/scylladb#29806
bc482bfdea