Remove route-proxy from the controller's repository, which it left for mesh-networking

The group's check composed route-proxy twice, here and in mesh-networking; the move is one delivery group
(issue 1126), so it leaves here in the same group. The tests that read its directory go with it.

Claude-Session: https://claude.ai/code/session_01NcbgfJ9Gum47zkFKWRaovL

internal/gosource/gosource_test.go

@@ -172,41 +172,6 @@ func TestANarrowedTreeHoldsTheBuildSourceAndNothingElse(t *testing.T) {
 	}
 }
 
-// This repository's own programs: the route proxy lives in its module's own Go module, so its build source is
-// not the controller's, and neither holds the other's command.
-func TestThisRepositorysProgramsHaveBuildSourcesOfTheirOwn(t *testing.T) {
-	root := filepath.Join("..", "..")
-	proxy, err := GoBuildSource(filepath.Join(root, "modules", "route-proxy"), "cmd/route-proxy")
-	if err != nil {
-		t.Fatal(err)
-	}
-	controller, err := GoBuildSource(root, "cmd/mesh-controller")
-	if err != nil {
-		t.Fatal(err)
-	}
-	for _, c := range []struct {
-		entries []string
-		name    string
-		file    string
-		held    bool
-	}{
-		{proxy, "the route proxy", "cmd/route-proxy/main.go", true},
-		{proxy, "the route proxy", "cmd/route-proxy/bus.go", true},
-		{proxy, "the route proxy", "go.mod", true},
-		{proxy, "the route proxy", "cmd/route-provider/main.go", false},
-		{proxy, "the route proxy", "README.md", false},
-		{controller, "the controller", "cmd/mesh-controller/main.go", true},
-		{controller, "the controller", "internal/conditions/condition.go", true},
-		{controller, "the controller", "internal/inventory/migrations/0001-nodes.sql", true},
-		{controller, "the controller", "modules/route-proxy/cmd/route-proxy/main.go", false},
-		{controller, "the controller", "README.md", false},
-	} {
-		if SourceHolds(c.entries, c.file) != c.held {
-			t.Errorf("%s: %s held %v, wanted %v", c.name, c.file, !c.held, c.held)
-		}
-	}
-}
-
 // C or assembly beside Go holds its package's directory whole — an include may name a file below it — and a
 // go.mod made between the module's root and a package is a change.
 func TestNativeSourcesHoldTheirDirectoryWhole(t *testing.T) {