Hermes should register for IBC events only

[ancazamfir]

Crate

relayer

Summary

hermes registers and gets all Tx events for all blocks. Instead hermes should register for IBC events only.
See more context in #1524

Problem Definition

Currently hermes gets all Tx events although it only processes the IBC events. When a block includes > 100 messages the client subscription may be closed if the events are not retrieved fast enough.

Proposal

To mitigate this problem hermes should register for IBC events only.

Acceptance Criteria

Significantly reduce the RPC error related to websocket client disconnects.

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