Define the artifact as Gerrit plugin

As it was previously defined it worked but made more complex
to import into Eclipse and testing it together with other
plugins.

There are no drawbacks in having the artifact defined as
a plugin and it would be aligned with what is also done
for other libModules, like cache-chroniclemap [1].

[1] https://gerrit.googlesource.com/modules/cache-chroniclemap/+/refs/heads/master/BUILD#10

Change-Id: I5247df884a92c1e7fdd05ffbee1a0e0341882eb3
diff --git a/BUILD b/BUILD
index be3ed79..7cb0408 100644
--- a/BUILD
+++ b/BUILD
@@ -7,12 +7,12 @@
     "PLUGIN_DEPS",
     "PLUGIN_DEPS_NEVERLINK",
     "PLUGIN_TEST_DEPS",
+    "gerrit_plugin",
 )
 
-java_library(
+gerrit_plugin(
     name = "global-refdb",
     srcs = glob(["src/main/java/**/*.java"]),
-    deps = PLUGIN_DEPS_NEVERLINK,
 )
 
 junit_tests(