Relook into dock and pool synchronization method

[sushanthakumar]

Is this a BUG REPORT or FEATURE REQUEST?:

/kind feature

What happened: There was a issue observed (https://github.com/opensds/opensds/issues/1189) that when opensds running in container mode goes down and comes up, there is some mismatch info wrt dock and pool lists at etcd side As the dock/pool identifiers are generated new , duplicate entries are observed at etcd for same pool/dock name. Also dock/pool info not cleared through unregister mechanism when opensds going down

The PR (https://github.com/opensds/opensds/pull/1190) fixes this issue by cross checking the entries in etcd and making sure no redundant infos are maintained at ectd

What you expected to happen: However, the flow can be relooked to confirm below points to check

1. dock/pool id regeneration logic correctness
2. Whether unregister flow can help to cleanup so that restart flow do not encounter old entries

How to reproduce it (as minimally and precisely as possible):

Anything else we need to know?:

Environment:

• Hotpot(release/branch) version:
• OS (e.g. from /etc/os-release):
• Kernel (e.g. uname -a):
• Install tools:
• Others: