MB-10057: removed useless misc:flush(checkpoint) calls
MB-10057: removed useless misc:flush(checkpoint) calls

Because checkpoint is not plain message but a gen_server:cast

Change-Id: Iba726f68f6bcb0eede22df820be8dd22ca0aa88f
Reviewed-on: http://review.couchbase.org/34034
Reviewed-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>

t3rm1n4l/ns_server,ceejatec/ns_server,mschoch/ns_server,mschoch/ns_server,t3rm1n4l/ns_server,membase/ns_server,ceejatec/ns_server,membase/ns_server,mschoch/ns_server,ceejatec/ns_server,nimishzynga/ns_server,mschoch/ns_server,nimishzynga/ns_server,daverigby/ns_server,mschoch/ns_server,ceejatec/ns_server,nimishzynga/ns_server,nimishzynga/ns_server,daverigby/ns_server,membase/ns_server,nimishzynga/ns_server,daverigby/ns_server,membase/ns_server,mschoch/ns_server,t3rm1n4l/ns_server,ceejatec/ns_server,membase/ns_server,t3rm1n4l/ns_server,membase/ns_server,ceejatec/ns_server,t3rm1n4l/ns_server,daverigby/ns_server,daverigby/ns_server,nimishzynga/ns_server