Increate gerrit user connection limit by 50%

Zuul has hit a scenario where a git repo update was unable to talk to
gerrit via ssh because it had reached its per user connection limit [0].
This then led to some openstack job failing [1].

The default limit (which we were using) is 64 connection per user.
Apparently this is not quite enough for a busy zuul? Increase this by
50% up to 96.

[0] http://paste.openstack.org/show/754741/
[1] http://lists.openstack.org/pipermail/release-job-failures/2019-July/001193.html

Change-Id: Ibeca2208485608f3b61aa716184165342bfcc3c9

modules/openstack_project/manifests/gerrit.pp

@@ -152,6 +152,7 @@ class openstack_project::gerrit (
     httpd_maxthreads                    => $httpd_maxthreads,
     httpd_maxqueued                     => $httpd_maxqueued,
     httpd_maxwait                       => $httpd_maxwait,
+    sshd_max_connections_per_user       => '96',
     commentlinks                        => $commentlinks,
     its_plugins                         => $its_plugins,
     its_rules                           => $its_rules,