add ulimits to dispatcher and identifier

[nvdk]

elixir services have issues on hosts with a lot of memory in recent docker versions, this prevents those.

some background in https://chat.semte.ch/channel/mu-semtech/thread/hrqTNCDqZjTebf8fx and https://www.couchbase.com/forums/t/couchbase-erl-child-setup-cpu-100-and-the-server-never-boots-up/32734