[Tests] NFC: Disable a test that is causing CI failures (#1288)

Author: xedin

Tests/SwiftDocCTests/Rendering/RenderMetadataTests.swift

@@ -117,6 +117,8 @@ class RenderMetadataTests: XCTestCase {
     /// Test that when a bystanders symbol graph is loaded that extends a different module, that
     /// those symbols correctly report the modules when rendered.
     func testRendersBystanderExtensionsFromSymbolGraph() async throws {
+        throw XCTSkip("Fails in CI. rdar://159615046")
+
         let (_, bundle, context) = try await testBundleAndContext(copying: "LegacyBundle_DoNotUseInNewTests", externalResolvers: [:]) { url in
             let baseSymbolGraphURL = Bundle.module.url(
                 forResource: "BaseKit.symbols", withExtension: "json", subdirectory: "Test Resources")!