Use CLI to configure max instances cache (#5177)

* Use CLI to configure max instances cache

* Fix tests

* Move default value into CLI

* Use SmallVec

* Apply review comments

* Get rid of `SmallVec`

Co-authored-by: Bastian Köcher <git@kchr.de>

substrate/primitives/api/test/tests/runtime_calls.rs

@@ -191,7 +191,11 @@ fn record_proof_works() {
 
 	// Use the proof backend to execute `execute_block`.
 	let mut overlay = Default::default();
-	let executor = NativeExecutor::<LocalExecutor>::new(WasmExecutionMethod::Interpreted, None);
+	let executor = NativeExecutor::<LocalExecutor>::new(
+		WasmExecutionMethod::Interpreted,
+		None,
+		8,
+	);
 	execution_proof_check_on_trie_backend::<_, u64, _>(
 		&backend,
 		&mut overlay,