[Payments] Update expiration data for enable-autofill-upi-vpa flag

The feature is still under development.

Change-Id: I1df61d578a7b70827f61d4484d1f80a5997d5f2a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2065669
Auto-Submit: Christos Froussios <cfroussios@chromium.org>
Reviewed-by: Matthias Körber <koerber@google.com>
Commit-Queue: Christos Froussios <cfroussios@chromium.org>
Cr-Commit-Position: refs/heads/master@{#743838}

chrome/browser/flag-metadata.json

@@ -1093,7 +1093,7 @@
   {
     "name": "enable-autofill-upi-vpa",
     "owners": ["cfroussios"],
-    "expiry_milestone": 82
+    "expiry_milestone": 88
   },
   {
     "name": "enable-background-blur",