Project-10: Replace ZooKeeperCacheLoader to fetch broker-metadata into Proxy/Discovery service with Metadata-store api

[rdhabalia]

Goal

ZookeeperCacheLoader is used by BrokerDiscoveryProvider, DiscoveryServiceServlet, Proxy to manage broker-metadata. Replace ZookeeperCacheLoader with Metadata-store API (PulsarResources)

Reference

Component: Discovery-service, Proxy-Service
Class-reference: "- ZookeeperCacheLoader
Affected Modules: BrokerDiscoveryProvider, DiscoveryServiceServlet, Proxy

Notes

1. Replace ZookeeperCacheLoader access with PulsarResources
2. Remove ZookeeperCacheLoader class