Extend tabbed web app experimental flags

This CL extends the expiry of:
 - enable-desktop-pwas-tab-strip
 - enable-desktop-pwas-tab-strip-link-capturing

Bug: 897314, 1078301
Change-Id: I1160964909d44d580b3cf394ce129adbbc7f3423
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2569141
Auto-Submit: Alan Cutter <alancutter@chromium.org>
Reviewed-by: Eric Willigers <ericwilligers@chromium.org>
Commit-Queue: Eric Willigers <ericwilligers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#833163}

chrome/browser/flag-metadata.json

@@ -1503,12 +1503,12 @@
   {
     "name": "enable-desktop-pwas-tab-strip",
     "owners": [ "desktop-pwas-team@google.com" ],
-    "expiry_milestone": 88
+    "expiry_milestone": 94
   },
   {
     "name": "enable-desktop-pwas-tab-strip-link-capturing",
     "owners": [ "desktop-pwas-team@google.com" ],
-    "expiry_milestone": 88
+    "expiry_milestone": 94
   },
   {
     "name": "enable-duet-tabstrip-integration",