[WebAuthn] Remove flag metadata for BLE authenticator support

The flag itself was already removed in r735677, this removes the
metadata from the json file.

Bug: 1046131
Change-Id: Id54ebfcd472e06f1bbfb870fa60e62bb97555ff1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2064815Reviewed-by: Nina Satragno <nsatragno@chromium.org>
Commit-Queue: Ken Buchanan <kenrb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#743120}

chrome/browser/flag-metadata.json

@@ -2039,11 +2039,6 @@
     "owners": [ "penghuang" ],
     "expiry_milestone": 90
   },
-  {
-    "name": "enable-web-authentication-ble-support",
-    "owners": [ "webauthn-team@google.com" ],
-    "expiry_milestone": 82
-  },
   {
     "name": "enable-web-authentication-cable-v2-support",
     "owners": [ "webauthn-team@google.com" ],