fix: simplify orphan runner judgment logic by removing checks that infringe on other checks

Author: stuartp44

lambdas/functions/control-plane/src/scale-runners/scale-down.ts

@@ -231,8 +231,7 @@ async function lastChanceCheckOrphanRunner(runner: RunnerList): Promise<boolean>
     `Runner '${runner.instanceId}' is '${state.status}' and is currently '${state.busy ? 'busy' : 'idle'}'.`,
   );
   const isOfflineAndBusy = state.status === 'offline' && state.busy;
-  const isOfflineAndIdle = state.status === 'offline' && !state.busy;
-  if (isOfflineAndBusy || isOfflineAndIdle) {
+  if (isOfflineAndBusy) {
     isOrphan = true;
   }
   logger.info(`Runner '${runner.instanceId}' is judged to ${isOrphan ? 'be' : 'not be'} orphaned.`);