Remove use of Tendermint RPC from View Service

[hdevalence]

Is your feature request related to a problem? Please describe.

Currently, the view service uses the Tendermint RPC's status endpoint to find out about what block height it should expect to sync to. The Tendermint RPC doesn't have very good performance and is vulnerable to DoS attacks. Also it has random lockups sometimes.

Describe the solution you'd like

Restrict use of the Tendermint RPC to transaction submission, and make the view service use only the pd gRPC endpoint while syncing.