Deprecate and remove web bundle directFromSellerSignals

The header-based version of directFromSellerSignals
(directFromSellerSignalsHeaderAdSlot) is unaffected.

Also, adds a WPT negative test, and uses a feature flag to control the
removal.

Usage metrics for web-bundle directFromSellerSignals are extremely low [0].

I2D&R thread [1].

[0] https://chromestatus.com/metrics/feature/timeline/popularity/5034

[1] https://groups.google.com/a/chromium.org/g/blink-dev/c/t9gHiTwV370

Bug: 384481095
Change-Id: I36d6ba9dbbeef4c434d00f5ba61cb1696bfbe11d

fledge/tentative/auction-config.https.window.js

@@ -17,8 +17,7 @@
 // META: variant=?51-55
 // META: variant=?56-60
 // META: variant=?61-65
-// META: variant=?66-70
-// META: variant=?71-last
+// META: variant=?66-last
 
 "use strict;"
 
@@ -350,27 +349,6 @@ makeTest({
   auctionConfigOverrides: { sellerSignals: { sig: BigInt(13) } },
 });
 
-makeTest({
-  name: 'directFromSellerSignals is invalid',
-  expect: EXPECT_PROMISE_ERROR,
-  expectPromiseError: EXPECT_EXCEPTION(TypeError),
-  auctionConfigOverrides: { directFromSellerSignals: "https://foo:99999999999" },
-});
-
-makeTest({
-  name: 'directFromSellerSignals is cross-origin with seller',
-  expect: EXPECT_PROMISE_ERROR,
-  expectPromiseError: EXPECT_EXCEPTION(TypeError),
-  auctionConfigOverrides: { directFromSellerSignals: "https://example.com" },
-});
-
-makeTest({
-  name: 'directFromSellerSignals has nonempty query',
-  expect: EXPECT_PROMISE_ERROR,
-  expectPromiseError: EXPECT_EXCEPTION(TypeError),
-  auctionConfigOverrides: { directFromSellerSignals: window.location.origin + "?foo=bar" },
-});
-
 makeTest({
   name: 'perBuyerSignals has invalid URL in a key',
   expect: EXPECT_PROMISE_ERROR,

fledge/tentative/direct-from-seller-signals.https.window.js

@@ -503,6 +503,17 @@ subsetTest(promise_test, async test => {
   assert_true(dfss);
 }, 'Test directFromSellerSignals feature detection.');
 
+// The version of directFromSellerSignals based on web bundles preceded the
+// header-based version -- the web bundle version has been deprecated and
+// removed.
+subsetTest(promise_test, async test => {
+  let dfss = false;
+  navigator.runAdAuction({
+      get directFromSellerSignals() { dfss = true; }
+  }).catch((e) => {});
+  assert_false(dfss);
+}, 'Negative test for deprecated and removed web-bundle directFromSellerSignals.');
+
 subsetTest(promise_test, async test => {
   const uuid = generateUuid(test);
   await fetchDirectFromSellerSignals({ 'Buyer-Origin': window.location.origin });