Fix ChaosInjector shard eligibility bug (#12231)

## Problem

ChaosInjector is intended to skip non-active scheduling policies, but
the current logic skips active shards instead.

## Summary of changes

- Fixed shard eligibility condition to correctly allow chaos injection
for shards with an Active scheduling policy.

storage_controller/src/service/chaos_injector.rs

@@ -107,7 +107,7 @@ impl ChaosInjector {
         // - Skip shards doing a graceful migration already, so that we allow these to run to
         //   completion rather than only exercising the first part and then cancelling with
         //   some other chaos.
-        !matches!(shard.get_scheduling_policy(), ShardSchedulingPolicy::Active)
+        matches!(shard.get_scheduling_policy(), ShardSchedulingPolicy::Active)
             && shard.get_preferred_node().is_none()
     }