vk: Update references to //ash/keyboard/ui/OWNERS.

In a previous patch we moved //ash/keyboard/ui/OWNERS to
//ash/keyboard/OWNERS, but forgot to update other files
that pointed to the old path.

Bug: 961568
Change-Id: I7d800c56ac4f1010a22912985c45534977173d29
No-Presubmit: True
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1647072
Auto-Submit: Darren Shen <shend@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Darren Shen <shend@chromium.org>
Commit-Queue: Darren Shen <shend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#666590}

chrome/browser/extensions/api/virtual_keyboard_private/OWNERS

-file://ash/keyboard/ui/OWNERS
+file://ash/keyboard/OWNERS
 
 # COMPONENT: UI>Input>VirtualKeyboard

chrome/browser/flag-metadata.json

@@ -1757,7 +1757,7 @@
   },
   {
     "name": "enable-virtual-keyboard",
-    "owners": [ "//ash/keyboard/ui/OWNERS" ],
+    "owners": [ "//ash/keyboard/OWNERS" ],
     // Useful for debugging the virtual keyboard on non-tablet devices.
     "expiry_milestone": -1
   },