(improvement)perf: Optimize DCAware/RackAware/TokenAware/HostFilter policies with host distance caching and overall perf. improvements (100's to 1000's of ns reduction, x1.1-2.9 improvement!)

(improvement)perf: Optimize DCAware/RackAware/TokenAware/HostFilter policies with host distance caching and overall perf. improvements (100's to 1000's of ns reduction, x1.1-2.9 improvement!) #841