topology_coordinator: add injection which makes upgrade get stuck

The injection will necessary for the test, introduced in the next
commit, which verifies that it's possible to recover from an upgrade of
raft topology which gets stuck.

service/topology_coordinator.cc

@@ -3048,6 +3048,9 @@ future<> topology_coordinator::do_upgrade_step(group0_guard guard) {
                 "topology_coordinator was started even though upgrade to raft topology was not requested yet")));
 
     case topology::upgrade_state_type::build_coordinator_state:
+        utils::get_local_injector().inject("topology_coordinator_fail_to_build_state_during_upgrade", [] {
+            throw std::runtime_error("failed to build topology coordinator state due to error injection");
+        });
         co_await build_coordinator_state(std::move(guard));
         co_return;