The patch sets different timeout to rpc api objects in OVS agent after
SIGTERM is received. Given timeout is configurable. This action prevents
long waiting for rpc call() methods to timeout and decreases amount of time
needed to successfully stopping OVS agent.
DocImpact
Closes-Bug: 1408334
Change-Id: I3026775e813a74bad9e0bca3be1f535212a2e417
(cherry picked from commit d3af7b0d2ebb2dd4da7e4a620eca8f554c124ec6)