Enable 5 Protected Audience and Fenced Frame features in Mode A/B

With the end of the Chrome-facilitated testing period, enable these features
in Modes A and B to provide a more consistent developer experience and
decrease the need for feature detection:
 * PA Real Time Reporting
 * PA multi-bid support
 * PA deprecatedReplaceInURN via auction config
 * PA multiple bidding contexts optimization
 * FF allow cross-origin subframes to send reportEvent() beacons

This was announced here:
 https://groups.google.com/a/chromium.org/g/blink-dev/c/WgGGPElrG9o

Change-Id: I7d26fb1ea908837557bf60cc8762245c409d0160
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6049396
Auto-Submit: Paul Jensen <pauljensen@chromium.org>
Reviewed-by: Shivani Sharma <shivanisha@chromium.org>
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Commit-Queue: Nasko Oskov <nasko@chromium.org>
Reviewed-by: Maks Orlovich <morlovich@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1390666}

fledge/tentative/generate-bid-browser-signals.https.window.js

@@ -33,6 +33,7 @@ subsetTest(promise_test, async test => {
     "adComponentsLimit": 40,
     "joinCount": 1,
     "bidCount": 0,
+    "multiBidLimit": 1,
     "prevWinsMs": []
   }
   let biddingLogicURL = createBiddingScriptURL(