Rename some build rules to meet expectation in JGit bazel build

This is a preparation to link JGit as a submodule instead of an
external Maven build dependency.

Change-Id: Icd470c32b6b0447b480bc494ea5ebf558c24e34c

lib/jetty/BUILD

diff --git a/lib/jetty/BUILD b/lib/jetty/BUILD
index 4f58b3d..521fd22 100644
--- a/lib/jetty/BUILD
+++ b/lib/jetty/BUILD
@@ -8,7 +8,7 @@
     name = "servlet",
     exports = [
         ":security",
-        "//lib:servlet-api_3_1",  # Different from the rest of gitiles-server.
+        "//lib:servlet-api",  # Different from the rest of gitiles-server.
         "@servlet//jar",
     ],
 )