Instantiate single YBClient instances for multiple methods

[vaibhav-yb]

Problem

We have helper methods which take in the configuration and create a YBClient instance of their own to execute RPC calls. However, they may end up creating multiple instances of YBClient which may lead to a memory/file leak if they're not garbage collected on time.

Another scenario where this could lead to a problem would be when heavily doing task/connector restarts as we will open a socket every time we create an instance of YBClient.

Solution

This PR is a small step to mitigate the problem a little by reusing the YBClient instances wherever necessary.

Additional notable changes in the PR:

1. Removed a redundant call to method YugabyteDBConnector#validateTserverConnection
2. Logging modifications to have more info in the logs - changed a few debug logs to info as they were only being logged once.
3. Some lint refactors included by the IDE itself.