Fix CI failures for deprecated attributeGraphEnabled and duplicate DPF dependency

Author: Kyle-Ye

Package.swift

@@ -386,6 +386,7 @@ private var hasSetupDPFDependency = false
 @MainActor
 func setupDPFDependency() {
     guard !hasSetupDPFDependency else { return }
+    hasSetupDPFDependency = true
     let privateFrameworkRepo: Package.Dependency
     if useLocalDeps {
         privateFrameworkRepo = Package.Dependency.package(path: "../DarwinPrivateFrameworks")

Tests/OpenAttributeGraphShimsTests/Attribute+DebugTests.swift

@@ -8,7 +8,7 @@ import OpenAttributeGraphShims
 import Testing
 
 @MainActor
-@Suite(.disabled(if: !attributeGraphEnabled, "Subgraph is not implemented on OAG"), .graphScope)
+@Suite(.disabled(if: attributeGraphVendor == .oag, "Subgraph is not implemented on OAG"), .graphScope)
 struct Attribute_DebugTests {
     @Test
     func directAttribute() {

Tests/OpenAttributeGraphShimsTests/MetadataDebugTests.swift

@@ -15,7 +15,7 @@ import AppKit
 private typealias PlatformView = NSView
 #endif
 
-@Suite(.disabled(if: !attributeGraphEnabled, "forEachField is not implemented for OAG"))
+@Suite(.disabled(if: attributeGraphVendor == .oag, "forEachField is not implemented for OAG"))
 struct MetadataDebugTests {
     struct Demo1 {
         var a: Int = .zero