chore(exec source): remove obsolete codec file and import (vectordotdev#18257)

Usage of `sized_bytes_codec` was removed in <vectordotdev#9337>.

Signed-off-by: Hugo Hromic <[email protected]>

Author: hhromic

src/sources/exec/mod.rs

@@ -42,8 +42,6 @@ use crate::{
 use lookup::{owned_value_path, path};
 use vector_core::config::{log_schema, LogNamespace};
 
-pub mod sized_bytes_codec;
-
 /// Configuration for the `exec` source.
 #[configurable_component(source("exec", "Collect output from a process running on the host."))]
 #[derive(Clone, Debug)]