Undeclaring gives a unit back the state it was found in, and removes a process the mesh made (hq ADR 0118, issue 130)

A service undeclared used to be stopped: unassigning the private network stopped the container
runtime, unassigning sshd would stop ssh, an uplink module would take the machine offline. The
host now records the unit's state when it first applies it and restores that on undeclare —
found running stays running; started by the mesh (the converge filter) is stopped again; nothing
is started on the way out; a pre-existing record leaves the unit alone.

An undeclared process had no removal at all and failed every apply on its node; its unit, timer
and bundle are now removed.

internal/apply/opening_test.go

@@ -359,7 +359,9 @@ func TestReturningToAdoptedLoadsTheGuardBeforeRemovingTheFilter(t *testing.T) {
 			return "", nil
 		}
 		converged := store.State{Resources: []store.Applied{
-			{ID: "nftables.load", Type: "service", Target: "mesh-filter.service", Origin: store.OriginDeclared}}}
+			{ID: "nftables.load", Type: "service", Target: "mesh-filter.service", Origin: store.OriginDeclared,
+				// The mesh loaded this filter at converge: it was not running before (novox/hq ADR 0118).
+				Found: &store.FoundUnit{State: "stopped"}}}}
 		_, state, err := applyWith(t, adopted(t, `{"taken":[]}`, withConf(dir)+","+guardFile), converged, run)
 		if !guardUpAtStop {
 			t.Errorf("stop fails %v: the derived filter was stopped before the guard was written", stopFails)