MB-8536: tidied redundant tasks in cbcollect_info

Perticularly there's no need to invoke netstat -an[p] twice and no
need to ls membase directories twice. Also as pointed out in the
ticket we grab syslogs separately so there's no need to cat them.

Change-Id: I46968967c4fcfdcd606ed83945f290b37b0d9e8f
Reviewed-on: http://review.couchbase.org/29441
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>