Initialize nesting client lazily
What does this MR do?
Calls nesting Init() when ErrNotInitialized is received.
Why was this MR needed?
Runner doesn't know when the nesting server restarts, so it doesn't know to call Init() before making other calls.
What's the best way to test this MR?
go test ./executors/internal/autoscaler
Can also test by restarting nesting and running another job.