Delete PartialBeaconState (#8591)

While reviewing Gloas I noticed we were updating `PartialBeaconState`. This code isn't used since v7.1.0 introduced hdiffs, so we can delete it and stop maintaining it 🎉

Similarly the `chunked_vector`/`chunked_iter` code can also go!


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

Co-Authored-By: Pawan Dhananjay <pawandhananjay@gmail.com>

beacon_node/store/src/errors.rs

@@ -1,4 +1,3 @@
-use crate::chunked_vector::ChunkError;
 use crate::config::StoreConfigError;
 use crate::hot_cold_store::{HotColdDBError, StateSummaryIteratorError};
 use crate::{DBColumn, hdiff};
@@ -13,9 +12,7 @@ pub type Result<T> = std::result::Result<T, Error>;
 #[derive(Debug)]
 pub enum Error {
     SszDecodeError(DecodeError),
-    VectorChunkError(ChunkError),
     BeaconStateError(BeaconStateError),
-    PartialBeaconStateError,
     HotColdDBError(HotColdDBError),
     DBError {
         message: String,
@@ -126,12 +123,6 @@ impl From<DecodeError> for Error {
     }
 }
 
-impl From<ChunkError> for Error {
-    fn from(e: ChunkError) -> Error {
-        Error::VectorChunkError(e)
-    }
-}
-
 impl From<HotColdDBError> for Error {
     fn from(e: HotColdDBError) -> Error {
         Error::HotColdDBError(e)