Stop composing ADR 0312's group grant, so deliveries to the media machine pass again

Since #256 delivered, the node-engine judges every read-write access by the path's group alone and
states six media modules unhealthy on ace, though they write their folders as the owner; every
delivery there fails its gate (hq issue 567). ADR 0325 replaces ADR 0312; until it is built, the
controller sends no grant, as before #256.

This reverts commit 3cfc121670.

cmd/mesh-controller/plan.go

@@ -947,14 +947,9 @@ func renderingFor(ctx context.Context, open *stores, node string,
 	if err != nil {
 		return catalogue.Rendering{}, inventory.Node{}, err
 	}
-	grantsGroups, err := engineGrantsGroups(ctx, inv, node)
-	if err != nil {
-		return catalogue.Rendering{}, inventory.Node{}, err
-	}
 	return catalogue.Rendering{
 		ReadsHealth:   readsHealth,
 		JudgesRoot:    judgesRoot,
-		GrantsGroups:  grantsGroups,
 		BusMembership: memberships[node],
 		Settings:      settings, Generators: gens, Grants: grants, Needed: needed, Foreseen: foreseen, Ports: ports,
 		Certificate: certificate, Authority: authority, Mesh: private, Names: names,
@@ -987,16 +982,6 @@ func engineJudgesRoot(ctx context.Context, inv *inventory.Inventory, node string
 	return had && stated.Contract >= link.RootContract, nil
 }
 
-// engineGrantsGroups says whether a machine's node-engine reads an access's `grant` (novox/hq ADR 0312), by its own
-// newest statement, for the same reason as engineReadsHealth: an older engine parses strictly.
-func engineGrantsGroups(ctx context.Context, inv *inventory.Inventory, node string) (bool, error) {
-	stated, had, err := inv.HealthOf(ctx, node)
-	if err != nil {
-		return false, err
-	}
-	return had && stated.Contract >= link.GrantContract, nil
-}
-
 // zonesInTheMesh is every zone a module in the mesh declares, where the mesh placed it (novox/hq ADR
 // 0199): the zone settled from that node's settings, the node's private address, the port the
 // answering listen is published on there.