Remove duplicate sync_tolerance_epochs config (#7109)

Delete duplicate sync tolerance epoch config in the HTTP API which is unused.

We introduced the `sync-tolerance-epoch` flag in this PR:

- https://github.com/sigp/lighthouse/pull/7030

Then refined it in this PR:

- https://github.com/sigp/lighthouse/pull/7044

Somewhere in the merge of `release-v7.0.0` into `unstable`, the config from the original PR which had been deleted came back. I think I resolved these conflicts, so my bad.

beacon_node/http_api/src/lib.rs

@@ -149,7 +149,6 @@ pub struct Config {
     #[serde(with = "eth2::types::serde_status_code")]
     pub duplicate_block_status_code: StatusCode,
     pub target_peers: usize,
-    pub sync_tolerance_epochs: Option<u64>,
 }
 
 impl Default for Config {
@@ -165,7 +164,6 @@ impl Default for Config {
             enable_beacon_processor: true,
             duplicate_block_status_code: StatusCode::ACCEPTED,
             target_peers: 100,
-            sync_tolerance_epochs: None,
         }
     }
 }