Remove redundant block argument from Indexer client.

[tzaffi]

Problem

The indexer client accepts redundant and error-causing parameters in a few of its methods. In particular:

• in several places the synonomous block and round_num are accepted. EG here
• in several places we alert users with DO NOT USE a particular param. EG here

Solution

Remove the offending parameters. As this is a breaking change, we may want to include it into a V3 upgrade.
We can start by deprecating usage ASAP.

Related Issues

#471

Urgency

Medium - this is mostly a nuisance, but it does cause confusion