Update notes for submitted changes

* SandeshStateMachine::WorkQueue task acquires cdbq_mutex_ [CdbIf::Db_AddColumn()] and then WorkQueue::mutex_[WorkQueue<CdbIf::CdbIfColList>::MayBeStartRunner()] when sandesh is received from the generator. At the same time, CdbIf::WorkQueue task acquires WorkQueue::mutex_ [WorkQueue<CdbIf::CdbIfColList>::RunnerDone()] and then cdbq_mutex_ [CdbIf::Db_Uninit()] when connection to the Analytics database is disconnected and TTransportException is raised in CdbIf::Db_BatchAddColumn(). This results in deadlock as the locks are acquired in the reverse direction in different tasks that run in parallel. Added a new function Db_UninitUnlocked() that would be invoked from SandeshGenerator::StartDbifReinit(). Closes-Bug: #1348563