ksv: Set KSV app flag owner and expiry milestone

We can likey remove the ability to disable this feature by M73.

Bug: None
Change-Id: I352eb60fb3f6915c140691f24a497df983a2b9c2
Reviewed-on: https://chromium-review.googlesource.com/c/1354261Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Michael Wasserman <msw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612195}

chrome/browser/flag-metadata.json

@@ -208,8 +208,8 @@
   },
   {
     "name": "ash-keyboard-shortcut-viewer-app",
-    // "owners": [ "your-team" ],
-    "expiry_milestone": 76
+    "owners": [ "msw" ],
+    "expiry_milestone": 73
   },
   {
     "name": "ash-shelf-color",