Update counters from fboss.ctrl.* to fboss.agent.*
Update counters from fboss.ctrl.* to fboss.agent.*

Summary:
- Updating only counters to use fboss.agent.* as part of this diff.

- Other mentions of fboss.ctrl.* are because of ctrl.thrift ['ctrl.thrift': 'neteng.fboss.ctrl'] I will send out a separate diff for the thrift changes by renaming it to agent.thrift and updating dependencies.

Reviewed By: aeckert

Differential Revision: D5100739

fbshipit-source-id: 88bb608a93f58cb97247517a87c7a3b2ac7f0f2d

peterlei/fboss,peterlei/fboss,peterlei/fboss,peterlei/fboss