* removes CowCachedExecutors (#22343)
Copy-on-write semantics for cached executors can be implemented by a
simple Arc<CachedExecutors> as opposed to CowCachedExecutors:
https://github.com/solana-labs/solana/blob/f1e2598ba/runtime/src/bank.rs#L244-L247
This will also avoid the need for double locking as in:
https://github.com/solana-labs/solana/blob/f1e2598ba/runtime/src/bank.rs#L3490-L3491
https://github.com/solana-labs/solana/blob/f1e2598ba/runtime/src/bank.rs#L3525-L3526
(cherry picked from commit c2389fc209)
# Conflicts:
# runtime/src/bank.rs
* removes backport merge conflicts
Co-authored-by: behzad nouri <behzadnouri@gmail.com>