Various minor fixes (#2860)

* Make sr-api-macros benchmark work again

It broke with 4f888f34.

* Give better indication of import progress

* Only send consensus info when explicitly enabled

This is only necessary for validators and they can
explicitly enable it via

	--telemetry-url 'wss://telemetry.polkadot.io 1'

(or some other endpoint)

* Remove unnecessary mutable

* Fix style