seal: Fail instantiate if new contract is below subsistence threshold (#6719)

* seal: Fail instantiate if new contract is below subsistence threshold

We need each contract that exists to be above the subsistence threshold
in order to keep up the guarantuee that we always leave a tombstone behind
with the exception of a contract that called `ext_terminate`.

* Fixup executor test

* Bump runtime

substrate/frame/contracts/src/exec.rs

@@ -426,7 +426,10 @@ where
 				)?;
 
 			// Error out if insufficient remaining balance.
-			if T::Currency::free_balance(&dest) < nested.config.existential_deposit {
+			// We need each contract that exists to be above the subsistence threshold
+			// in order to keep up the guarantuee that we always leave a tombstone behind
+			// with the exception of a contract that called `ext_terminate`.
+			if T::Currency::free_balance(&dest) < nested.config.subsistence_threshold() {
 				Err("insufficient remaining balance")?
 			}
 
@@ -1016,7 +1019,7 @@ mod tests {
 
 			let mut gas_meter = GasMeter::<Test>::new(GAS_LIMIT);
 
-			let result = ctx.instantiate(1, &mut gas_meter, &code, vec![]);
+			let result = ctx.instantiate(cfg.subsistence_threshold(), &mut gas_meter, &code, vec![]);
 			assert_matches!(result, Ok(_));
 
 			let mut toks = gas_meter.tokens().iter();
@@ -1306,7 +1309,7 @@ mod tests {
 			set_balance(&ALICE, 100);
 
 			let result = ctx.instantiate(
-				1,
+				cfg.subsistence_threshold(),
 				&mut GasMeter::<Test>::new(GAS_LIMIT),
 				&input_data_ch,
 				vec![1, 2, 3, 4],
@@ -1549,7 +1552,7 @@ mod tests {
 				// Instantiate a contract and save it's address in `instantiated_contract_address`.
 				let (address, output) = ctx.ext.instantiate(
 					&dummy_ch,
-					15u64,
+					Config::<Test>::subsistence_threshold_uncached(),
 					ctx.gas_meter,
 					vec![]
 				).unwrap();
@@ -1679,7 +1682,7 @@ mod tests {
 			set_balance(&ALICE, 100);
 
 			let result = ctx.instantiate(
-				1,
+				cfg.subsistence_threshold(),
 				&mut GasMeter::<Test>::new(GAS_LIMIT),
 				&rent_allowance_ch,
 				vec![],