Function try_read_varint_meta3_from_tstore 

pub(crate) fn try_read_varint_meta3_from_tstore<S: TrieBuilderStore>(
    start: u8,
    remainder: &mut S,
) -> Option<usize>

Reads and removes a varint with 3 bits of metadata from a TrieBuilderStore.

Returns the varint value.