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/client/executor/src/integration_tests/mod.rs

@@ -46,6 +46,7 @@ fn call_in_wasm<E: Externalities>(
 		Some(1024),
 		HostFunctions::host_functions(),
 		true,
+		8,
 	);
 	executor.call_in_wasm(
 		&WASM_BINARY[..],
@@ -511,6 +512,7 @@ fn should_trap_when_heap_exhausted(wasm_method: WasmExecutionMethod) {
 		Some(17),  // `17` is the initial number of pages compiled into the binary.
 		HostFunctions::host_functions(),
 		true,
+		8,
 	);
 	executor.call_in_wasm(
 		&WASM_BINARY[..],