Disable autogc in jgit

By default, git-receive-pack will run auto gc after receiving data from
git-push and updating refs.

Disable this behavior to avoid the additional load it creates: gc should
be scheduled as a separate process.

Bug: Issue 13702
Change-Id: I9d7ad967f451446d053f5a62e852948205d03f53
diff --git a/gerrit/etc/jgit.config.template b/gerrit/etc/jgit.config.template
index 630cd94..d65673a 100644
--- a/gerrit/etc/jgit.config.template
+++ b/gerrit/etc/jgit.config.template
@@ -1,2 +1,5 @@
 [core]
-  trustFolderStat = {{ TRUST_FOLDER_STAT }}
\ No newline at end of file
+  trustFolderStat = {{ TRUST_FOLDER_STAT }}
+
+[receive]
+  autogc = false
\ No newline at end of file