Companion for #6067 (#1110)

* Companion to #6067

* Fix tests?

* Use AvailableBlockLimit instead of hardcoding the value.

* Bump substrate.

polkadot/runtime/test-runtime/src/lib.rs

@@ -144,6 +144,7 @@ impl system::Trait for Runtime {
 	type DbWeight = ();
 	type BlockExecutionWeight = BlockExecutionWeight;
 	type ExtrinsicBaseWeight = ExtrinsicBaseWeight;
+	type MaximumExtrinsicWeight = MaximumBlockWeight;
 	type MaximumBlockLength = MaximumBlockLength;
 	type AvailableBlockRatio = AvailableBlockRatio;
 	type Version = Version;