[ios] Add flag ownership for fernandex

iOS flag owners were asked to claim ownership and state an expiry in
this announcement email:
https://groups.google.com/a/google.com/g/bling-team/c/7YC_3l6yEzo/m/1-iZg1fPAAAJ

This is one of several CLs that adds iOS flag ownership information into
flag-metadata.json.

The owner of these flags was identified via git blame. A placeholder
expiry milestone of M86 was added. Please either LGTM, or suggest a new
owner and/or expiry.

Bug: 1058614
Change-Id: I87a7166d964b3229661b125e71288e9bf0eec6f6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2095397Reviewed-by: edchin <edchin@chromium.org>
Reviewed-by: Jérôme Lebel <jlebel@chromium.org>
Commit-Queue: edchin <edchin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748712}

chrome/browser/flag-metadata.json

@@ -435,6 +435,11 @@
     "owners": [ "dullweber" ],
     "expiry_milestone": 78
   },
+  {
+    "name": "clear-synced-data",
+    "owners": [ "fernandex" ],
+    "expiry_milestone": 86
+  },
   {
     "name": "click-to-call-context-menu-selected-text",
     "owners": [ "//chrome/browser/sharing/OWNERS" ],