Fix: Clean up test queues after subscription update

## Problem After updating subscription links, the test latency queues (testLatency/testLatencyIndepends) still contain tags of servers that no longer exist, causing testing issues. ## Root Cause In loadFrom() function, when replacing existing server list with new one: - Server list is updated correctly - Old latency values are preserved for matching servers - But test queues are not cleaned up, still containing removed server tags ## Solution After updating server list in loadFrom(), clean up test queues to remove any tags of servers that no longer exist in the updated list. ## Impact - Fixes latency testing issues after subscription update - Ensures test queues only contain valid server tags - Maintains backward compatibility