Remove explicit JGit dependency

It's exported in plugin-api and this library is added to the deps
in gerrit_plugin() itself.

Change-Id: I006faecd020e8df45d85cb63cd7af90e14881628

BUCK

diff --git a/BUCK b/BUCK
index 67dc671..0517fad 100644
--- a/BUCK
+++ b/BUCK
@@ -10,7 +10,6 @@
   ],
   # Deps shared with Gerrit but not in the plugin API.
   provided_deps = [
-    '//lib/jgit:jgit',
     '//lib/commons:net',
   ],
 )