Currently, we send a single SIGKILL to the shim process
once and then we spin in a loop where we use kill(pid, 0)
to detect when the pid has disappeared completely.
Unfortunately, this has a race condition since pids can be reused causing us
to spin in an infinite loop when that happens.
This adds a timeout to this loop which logs a warning and exits the
infinite loop.
Signed-off-by: Ashray Jain <ashrayj@palantir.com>