decl_module! macro: use 'frame_system' instead of system as default ident (#6500)

* Use frame_system as default ident.

* Remove unused 'frame_system' to 'system' renaming.

* Fix construct_runtime_ui tests.

* Rename system to frame_system in sudo/utility pallet test.

* Bump runtime impl_version.

* Update formatting.

substrate/frame/utility/src/lib.rs

@@ -64,7 +64,7 @@ use frame_support::{
 	traits::{OriginTrait, UnfilteredDispatchable},
 	weights::{Weight, GetDispatchInfo, DispatchClass}, dispatch::PostDispatchInfo,
 };
-use frame_system::{self as system, ensure_signed, ensure_root};
+use frame_system::{ensure_signed, ensure_root};
 use sp_runtime::{DispatchError, DispatchResult, traits::Dispatchable};
 
 mod tests;

substrate/frame/utility/src/tests.rs

@@ -34,7 +34,7 @@ impl_outer_origin! {
 }
 impl_outer_event! {
 	pub enum TestEvent for Test {
-		system<T>,
+		frame_system<T>,
 		pallet_balances<T>,
 		utility,
 	}
@@ -132,7 +132,7 @@ pub fn new_test_ext() -> sp_io::TestExternalities {
 }
 
 fn last_event() -> TestEvent {
-	system::Module::<Test>::events().pop().map(|e| e.event).expect("Event expected")
+	frame_system::Module::<Test>::events().pop().map(|e| e.event).expect("Event expected")
 }
 
 fn expect_event<E: Into<TestEvent>>(e: E) {