In functional tests of the ovsdb_monitor, sometimes during high load
of the host where tests are run, "error" message from the killed process
can be received by neutron's async_process after new process was
already spawned.
And that causes failure of the test as new ovsdb_monitor will not
receive events which are expected.
To workaround that issue this patch adds sleep for few seconds between
stopping old and starting new ovsdb_monitor process.
Closes-Bug: #1907068
Change-Id: Ib37a52a623943ae4b6a4ec829c5d12a74514e86c
(cherry picked from commit 0aa7f5b511)