depend-o-pocalipse (#9450)

Remove unneeded dependencies and dev-dependencies.
Made self_destruct test not dependent on wasm bin size.  
Updated code related to deprecated warning on tracing-subscriber `scope()` 
( See https://github.com/tokio-rs/tracing/issues/1429 )

substrate/frame/example-offchain-worker/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "pallet-example-offchain-worker"
-version = "3.0.0-dev"
+version = "4.0.0-dev"
 authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2018"
 license = "Unlicense"