Disable journal preallocation

MongoDB at start time measures write latency for cases with
and without preallocation.
If difference is larger than 2ms MongoDB starts to allocate
2Gb journal. During allocation it is not able to listen for
requests, so cluster initialization fails.

This change make mongobd starts faster for succesful cluster
initialization.

Change-Id: I55ff6076b0c21a5df93231b2c789d16256c4c784
Closes-Bug: PROD-27116
diff --git a/mongodb/files/mongodb.conf b/mongodb/files/mongodb.conf
index a126120..34ef7f6 100644
--- a/mongodb/files/mongodb.conf
+++ b/mongodb/files/mongodb.conf
@@ -13,6 +13,9 @@
 dbpath=/var/lib/mongodb
 journal=true
 
+# Disable journal preallocation for predictable service start time
+nopreallocj=true
+
 {%- if server.authorization.get('enabled', False) %}
 auth=true
 {%- endif %}