multi: add DeleteChannelEdges to VersionedGraph

Add version-aware DeleteChannelEdges method to VersionedGraph and
update call sites in graph builder, rpcserver, and server to use
versioned graphs. This ensures channel deletion operations are
properly scoped to the correct gossip version.

graph/db/graph_test.go

@@ -153,6 +153,7 @@ var versionedTests = []versionedTest{
 func TestVersionedDBs(t *testing.T) {
 	t.Parallel()
 
+	// Run all v1 tests.
 	for _, vt := range versionedTests {
 		vt := vt