Fix RecoveryIntegrationSingleNodeTest failure

The InMemoryJournal may not have received all the persisted messages
by the time it checks the expected size of the journal so added a latch/wait
for he expected messages..

Change-Id: I8f050b9375f5e3e74749c17e831add21d09d1831
Signed-off-by: Tom Pantelis <tompantelis@gmail.com>
(cherry picked from commit 75a222ffd227bb9f2aeef8ee7998f8df6f529bf8)