Adding flag owner for enable-suggestions-with-substring-match

TBR=ellyjones@chromium.org

Change-Id: Ide1f29008cd3840ec13c2252a279a76a4f5efdec
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1617628
Commit-Queue: Tommy Martino <tmartino@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Reviewed-by: Tommy Martino <tmartino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#660840}

chrome/browser/flag-metadata.json

@@ -1553,8 +1553,8 @@
   },
   {
     "name": "enable-suggestions-with-substring-match",
-    // "owners": [ "your-team" ],
-    "expiry_milestone": 76
+    "owners": [ "tmartino" ],
+    "expiry_milestone": 77
   },
   {
     "name": "enable-surfacecontrol",