Remove /lighthouse/analysis/block_rewards APIs (#8935)

Mark pointed out that these APIs will require updates for Gloas, so I figured we may as well get rid of them. As far as I know, blockprint was the only use case and it is now defunct. The consensus block value is included in getBlock API responses, so there's no reason for VCs to use the `POST` API, and there is now a standard API for the rewards of canonical blocks. The SSE event was non-standard, and likely only used by blockprint as well.


Co-Authored-By: Michael Sproul <michael@sigmaprime.io>

beacon_node/beacon_chain/src/block_verification.rs

@@ -1571,24 +1571,6 @@ impl<T: BeaconChainTypes> ExecutionPendingBlock<T> {
 
         metrics::stop_timer(committee_timer);
 
-        /*
-         * If we have block reward listeners, compute the block reward and push it to the
-         * event handler.
-         */
-        if let Some(ref event_handler) = chain.event_handler
-            && event_handler.has_block_reward_subscribers()
-        {
-            let mut reward_cache = Default::default();
-            let block_reward = chain.compute_block_reward(
-                block.message(),
-                block_root,
-                &state,
-                &mut reward_cache,
-                true,
-            )?;
-            event_handler.register(EventKind::BlockReward(block_reward));
-        }
-
         /*
          * Perform `per_block_processing` on the block and state, returning early if the block is
          * invalid.