dockerised_local_env: Fix ssh private key permission

So that only user can read it as a file. Before this change, gerrit-2
used to exit after ssh warning about wrong permissions for that file.

Bug: Issue 12493
Change-Id: I37534fd4e5fd1792233f24a57a70ed54d6941a2f

dockerised_local_env/gerrit-2/docker-entrypoint.sh

diff --git a/dockerised_local_env/gerrit-2/docker-entrypoint.sh b/dockerised_local_env/gerrit-2/docker-entrypoint.sh
index e13f768..06f928f 100755
--- a/dockerised_local_env/gerrit-2/docker-entrypoint.sh
+++ b/dockerised_local_env/gerrit-2/docker-entrypoint.sh
@@ -11,8 +11,11 @@
 
   echo "Waiting for gerrit1 server to become available."
   sleep 120
+
+  chmod go-r /var/gerrit/.ssh/id_rsa
   ssh-keyscan -t rsa -p 29418 gerrit-1 > /var/gerrit/.ssh/known_hosts
   ssh -p 29418 admin@gerrit-1 replication start
+
   echo "Waiting for replication to complete."
   sleep 30
 fi