Extend printer status feature flags

Extending to M91 for new enterprise printer status icons introduced in
M89.

Change-Id: I7c51781d77aa6a5a575460bcd2a03d80566a3533
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2616984
Auto-Submit: Gavin Williams <gavinwill@chromium.org>
Reviewed-by: Zentaro Kavanagh <zentaro@chromium.org>
Commit-Queue: Zentaro Kavanagh <zentaro@chromium.org>
Cr-Commit-Position: refs/heads/master@{#841582}

chrome/browser/flag-metadata.json

@@ -3982,12 +3982,12 @@
   {
     "name": "printer-status",
     "owners": [ "gavinwill", "cros-peripherals@google.com" ],
-    "expiry_milestone": 88
+    "expiry_milestone": 91
   },
   {
     "name": "printer-status-dialog",
     "owners": [ "gavinwill", "cros-peripherals@google.com" ],
-    "expiry_milestone": 90
+    "expiry_milestone": 91
   },
   {
     "name": "privacy-advisor",