Extend expiry of chrome://flags#web-bundles

And updates the owners list.

Bug: 1073310
Change-Id: I948d0d8e4aed6c825f3e0846b532fe880f8cedae
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2462757Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Kunihiko Sakamoto <ksakamoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815487}

chrome/browser/flag-metadata.json

@@ -4698,8 +4698,8 @@
   },
   {
     "name": "web-bundles",
-    "owners": [ "toyoshim", "ksakamoto", "horo", "kinuko" ],
-    "expiry_milestone": 87
+    "owners": [ "ksakamoto", "horo", "kinuko" ],
+    "expiry_milestone": 90
   },
   {
     "name": "web-contents-occlusion",