MB-6726: decrease overhead of capi_set_view_manager

Looks like logging of each call's args twice plus some excessive
calls, plus some duplicated checks were eating quite significant
amount of CPU.

In my swap rebalance 3-total-1-swap tests it was speedup from about 10
minutes down to 6. Most likely this is some fixed cost (independent
from size of data), but it's still a good win to have.

Change-Id: I1bf29e3859fa64d2c4180fd06f5b5738b06b5e5e
Reviewed-on: http://review.couchbase.org/23669
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>