remove connected disconnected state only (#3868)

* remove connected disconnected state from overseer

* foo

* split new partial

* fix

* refactor init code to not require a `OverseerHandle` when we don't have an overseer

* intermediate

* fixins

* X

* fixup

* foo

* fixup

* docs

* conditional

* Update node/service/src/lib.rs

* review by ladi