Remove leftover per node keys upon switching to 3.0 compat mode.
Remove leftover per node keys upon switching to 3.0 compat mode.

Change-Id: Ic1e447f263513d096c455a6e7d6f7c9ae8871471
Reviewed-on: http://review.couchbase.org/35291
Reviewed-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>

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