Integrate tracing (#6339)

Tracing Integration
- [reference](5bbf1859e9/projects/project-ideas.md (L297))


  - [x] replace slog & log with tracing throughout the codebase
- [x] implement custom crit log
- [x] make relevant changes in the formatter
- [x] replace sloggers
- [x] re-write SSE logging components

cc: @macladson @eserilev

beacon_node/beacon_chain/src/pre_finalization_cache.rs

@@ -2,9 +2,9 @@ use crate::{BeaconChain, BeaconChainError, BeaconChainTypes};
 use itertools::process_results;
 use lru::LruCache;
 use parking_lot::Mutex;
-use slog::debug;
 use std::num::NonZeroUsize;
 use std::time::Duration;
+use tracing::debug;
 use types::non_zero_usize::new_non_zero_usize;
 use types::Hash256;
 
@@ -87,10 +87,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             // blocks have been flushed out. Solving this issue isn't as simple as hooking the
             // beacon processor's functions that handle failed blocks because we need the block root
             // and it has been erased from the `BlockError` by that point.
-            debug!(
-                self.log,
-                "Pre-finalization lookup cache is full";
-            );
+            debug!("Pre-finalization lookup cache is full");
         }
         Ok(false)
     }