Server: avoid re-use of recent ParticleSpawner and Sound IDs (#14045)

This improves the reliability when removing and re-adding handles quickly.
Looping through the entire ID range avoids collisions caused by any race condition.

src/server.h

@@ -695,7 +695,7 @@ class Server : public con::PeerHandler, public MapEventReceiver,
 		Sounds
 	*/
 	std::unordered_map<s32, ServerPlayingSound> m_playing_sounds;
-	s32 m_next_sound_id = 0; // positive values only
+	s32 m_playing_sounds_id_last_used = 0; // positive values only
 	s32 nextSoundId();
 
 	ModStorageDatabase *m_mod_storage_database = nullptr;