Fix managedRenterContractsAndUtilities to only mark good hosts as used within siafiles

MERGE REQUEST

Overview

Previously we would mark a host as used within a siafile if we had a contract with it. That doesn't work for nodes with a ton of contracts though since many bad contracts would result in files not being repaired. So this MR changes the code to only mark hosts as used which contribute towards redundancy to make sure we prune those which don't in case we ever need to defrag a chunk.

Example for Visual changes (ie Screenshot)

Issues Closed

Checklist

Review and complete the checklist to ensure that the MR is complete before assigned to an approver.

• All new methods, or updating methods have clear docstrings
• Testing added or updated for new methods
• Any new packages are added to Makefile and .gitlab-ci.yml
• API documentation updated for API updates
• Module README.md updated for changes to work flow
• Issue added to Sia-UI repo for new supporting features
• Changelog updated