HDDS-14336. Remove OM Proxy duplication in HadoopRpcOMFailoverProxyProvider

[ivandika3]

What changes were proposed in this pull request?

HadoopRpcOMFailoverProxyProvider contains two maps regarding OM proxy info 1) omProxyInfos (OMProxyInfo) 2) omProxies (ProxyInfo) from OMFailoverProxyProviderBase. This causes some confusion since OMProxyInfo has the same name as Hadoop's ProxyInfo, but does not contain any internal proxy unlike ProxyInfo. It also makes some use cases require to check two different maps, which is tedious.

We can try to unify it by making OMProxyInfo extends ProxyInfo instead and remove omProxyInfos from HadoopRpcOMFailoverProxyProvider.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-14336

How was this patch tested?

Existing CI (https://github.com/ivandika3/ozone/actions/runs/20672551837)

[ivandika3]

Technically, we should be able to remove omNodeIDList and omNodeAddressMap as well by unifying it in the omProxies. This requires the usage of OmProxyInfo for both GrpcOMFailoverProxyProvider and HadoopRpcOMFailoverProxyProvider (i.e. by changing Map<String, ProxyInfo<T>> to Map<String, OmProxyInfo<T>> omProxies).

Edit: Removed omNodeAddressMap. omNodeIDList is renamed to omNodesInOrder and cannot be removed since it defines the ordering of OM nodes failover. Although omProxies uses Map that does not define any ordering, Map also does not ensure that the key ordering will be different each time.