DNS Cache Enhancement

[rahim-kanji]

• Introduce a 5% jitter to cache_ttl to increase the likelihood of distributing DNS resolution across multiple intervals, reducing the chance of simultaneous expiry times.

• Add a small delay after queuing, allowing DNS resolver thread time to process as many hostnames as possible before assessing the need for additional helper threads. This prevents 'DNS resolver queue too big' warnings from filling up the logs.