finagle-stats: Update BUILD file to be more narrow
finagle-stats: Update BUILD file to be more narrow

Problem / Solution

We can narrow the globs for finagle/finagle-stats since it's just one file.

JIRA Issues: CSL-7428

Differential Revision: https://phabricator.twitter.biz/D256506

twitter/finagle,twitter/finagle,luciferous/finagle,luciferous/finagle,twitter/finagle,luciferous/finagle,luciferous/finagle,luciferous/finagle,twitter/finagle,twitter/finagle,luciferous/finagle