database: increase semaphore max queue size

Queued reads don't take 10KB (not even 1KB) for years now. But the real
motivation of this patch is that due to a soon-to-come change to
admission we expect larger queues especially in tests, so be more
forgiving with queue sizes.

database.hh

@@ -1250,8 +1250,8 @@ private:
     ::cf_stats _cf_stats;
     static constexpr size_t max_count_concurrent_reads{100};
     size_t max_memory_concurrent_reads() { return _dbcfg.available_memory * 0.02; }
-    // Assume a queued read takes up 10kB of memory, and allow 2% of memory to be filled up with such reads.
-    size_t max_inactive_queue_length() { return _dbcfg.available_memory * 0.02 / 10000; }
+    // Assume a queued read takes up 1kB of memory, and allow 2% of memory to be filled up with such reads.
+    size_t max_inactive_queue_length() { return _dbcfg.available_memory * 0.02 / 1000; }
     // They're rather heavyweight, so limit more
     static constexpr size_t max_count_streaming_concurrent_reads{10};
     size_t max_memory_streaming_concurrent_reads() { return _dbcfg.available_memory * 0.02; }