Bazel: Fix lint warning flagged by buildifier

Buildifier warns about duplicate rule name gitiles:

BUILD:24: duplicated-name: A rule with name "gitiles" was already found
on line 4. Even if it's valid for Blaze, this may confuse other tools.
Please rename it and use different names.

Refactor the build and create gitiles-servlet resource jar in advance.
In this case we do not need to create intermediate plugin artifact any
more and can merge into the final artifact the gitiles-servlet resource

Change-Id: I58f7389725eb0fb1862fc35b4222f7757384d1dc
2 files changed