Moves all test runtimes to use derive_impl (#2409)

Step in https://github.com/paritytech/polkadot-sdk/issues/171

This PR adds `derive_impl` on all `frame_system` config impls for mock
runtimes. The overridden configs are maintained as of now to ensure
minimal changes.

---------

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

substrate/frame/democracy/src/tests.rs

@@ -20,7 +20,7 @@
 use super::*;
 use crate as pallet_democracy;
 use frame_support::{
-	assert_noop, assert_ok, ord_parameter_types, parameter_types,
+	assert_noop, assert_ok, derive_impl, ord_parameter_types, parameter_types,
 	traits::{
 		ConstU32, ConstU64, Contains, EqualPrivilegeOnly, OnInitialize, SortedMembers,
 		StorePreimage,
@@ -77,6 +77,8 @@ parameter_types! {
 			Weight::from_parts(frame_support::weights::constants::WEIGHT_REF_TIME_PER_SECOND, u64::MAX),
 		);
 }
+
+#[derive_impl(frame_system::config_preludes::TestDefaultConfig as frame_system::DefaultConfig)]
 impl frame_system::Config for Test {
 	type BaseCallFilter = BaseFilter;
 	type BlockWeights = BlockWeights;